GZDoom game configuration: added support for distinct upper/middle/lower sidedef brightness levels. Resolves #694

Internal, build tools: use origin/master to get commits count and current hash instead of local master.

Added, Textures Browser: redesigned textures list. Textures preview size can now be changed from the Textures Browser window. Folders are now shown in the textures list.
Fixed, Script Editor: Find and Replace window now sets keyboard focus to the input textbox when opening the window/switching between tabs.
Fixed, Nodes Viewer mode: SEGS overflows were not handled, causing a crash. Also extended SEGS limit is now used.
Updated ZDoom_DECORATE.cfg (A_SetSize).

Fixed: stored windows positions were not checked against current screen bounds, which may have resulted in windows being shown off-screen.

Added "Next View Mode" and "Previous View Mode" actions.
Removed "Replace unused textures" checkboxes from Edit Linedefs window.
Fixed, SNDINFO parser: commented $ambient sound definitions were treated as editor comments (and still processed).

Fixed, Edit Linedefs window: textures on selected sidedefs must be updated when toggling "Replace unused textures" setting.
Fixed, Texture Selector control: in some cases actual textures were never loaded/displayed when "Replace unused textures" setting was disabled.
Fixed, Script Editor: auto-completion list is no longed displayed when editing comments, includes or strings.

Added, Linedef Edit window: added "Replace unused textures" checkbox. When disabled, textures on unused sidedef parts won't be replaced when changing textures. For example, you can now replace sidedef textures of the whole map at once without assigning middle textures to all double-sided sidedefs.
Updated documentation ("Compiling GZDoom Builder" - added "Quick start guide" section).
Updated ZDoom_DECORATE.cfg.

Visual mode: fog distance calculation is now much closer to GZDoom one.
Visual mode: thing brightness calculation when a thing is affected by floor glow is now much closer to GZDoom one.
Linedef edit window, UDMF: added "Reset front/back brightness" buttons.
Sector edit window, UDMF: added "Reset ceiling/floor brightness" buttons.
Internal, Visual mode, Things mode: persistent event lines are now updated only when map objects are changed instead of doing it on every display redraw.
Internal: improved Dictionary lookup times when using map objects and textures as keys.
Internal: added "Release + Profiler" solution configuration.
Updated ZDoom_ACS.cfg (Warp).

UDMF: implemented 'moreids' handling. Currently this includes the core stuff, new TagsPicker control in Edit Sector/Linedef windows and updated Sector/Linedef Info panels.

Changed, Linedef/Thing Edit windows: when using ACS specials and choosing a script with arguments, appropriate action argument names are replaced with script argument names.
Changed, Linedef/Thing Info panel: when displaying a linedef/thing with an ACS special, which uses a script with arguments, appropriate action argument names are replaced with script argument names.
Changed, Sector/Linedef/Thing Edit windows, Comments tab: window is no longer closed when pressing Enter while editing a comment. Newline is inserted instead.
Changed: Script Editor window is now toggled to normal state when pressing "Show Script Editor" button if said window was already open, but minimized.
Fixed: in some cases action arguments were not cleared during setup when displaying multiple map elements with mixed argument values.
Internal: added ArgumentsControl.

Sectors, Linedefs, Things modes: comment icons for appropriate map elements with comments are now rendered in these modes. This can be disabled using either the new "Toggle Comments" action, "View -> Show Comments" menu item, or "Show Comments" button on the main toolbar.

Changed, Thing and Linedef Edit Forms, script selector drop-downs: scripts from include files are now shown using different color and after the map scripts.
Fixed, Visual mode, UDMF: sector geometry cache was not updated after using "Match Brightness" and "Change Brightness" actions on ceilings, so the changes made by them were not visible when using Classic modes in "View Ceiling Textures" mode.
Fixed, Visual mode, UDMF: "Match Brightness" and "Change Brightness" actions set brightness incorrectly in some cases.
Fixed: ACS script names gathering logic was unable to process relative #include and #import paths (like '#import "..\acs\qtilt.acs"').
Updated ZDoom_DECORATE.cfg.

High-DPI: fixed alignment issues in Sector, Thing, Linedef and Vertex Edit Forms, also in Open Map Options and Map Options Forms.
Changed: Thing Browser Form is now resizeable.
Changed: made default Texture Browser Form size smalled, so it properly fits the screen when using low display resolution.

Thing\Linedef Edit Form: added some tooltips.
Some cosmetic layout changes in LinedefEditForm.

Cosmetic changes in Sector Info Panel and Thing Browser Control.
ArgumentInfo: fixed a crash when enum specified in a game configuration doesn't exist.
Updated Hexen and ZDoom linedef configs.
Updated ZDoom_DECORATE.cfg

Thing, Sector, Linedef edit forms, UDMF: fixed more cases when missing game configuration blocks crashed the forms.
Thing and Sector edit forms, UDMF: fixed some minor layout issues.

Added long texture names support (enabled when "longtexturenames" game configuration property is set to true and "Use long texture names" check box is checked in Map Options).
Open Map in Current WAD: resources are now reloaded when current and target map's resources don't match.
Added some boilerplate to UniversalParser and PK3FileImage.
Internal: ImageSelectorControl now has "UsePreviews" property.
Internal: added ConfigurablePictureBox.
Updated ZDoom_DECORATE.cfg.

Linedef Edit Form, UDMF: "Lock number" now has a drop-down with supported key types (no LOCKDEFS support (yet?)). You can still type lock number manually.

Changed: thing sprite is now displayed in ThingBrowserControl.

Linedef Edit form: resized controls to show all flags without scrolling.
Updated ACS and DECOTARE ZDoom configurations.

Updated MissingThing icon.
More changes in ZDoom_linedefs.cfg and Hexen_linedefs.cfg.

Changed FormBorderStyle from FixedToolWindow to FixedDialog. GZDB should no longer disappear from the alt-tab list when a child form is opened.

Visual mode: "Lower/Raise Floor/Ceiling" actions now work on surfaces with sector slopes.
Cosmetic: numeric textboxes, which support relative values, now have differently colored text and a tooltip.
Internal: renamed Sector.CeilingSlopeOffset to Sector.CeilSlopeOffset, Sector.CeilingSlope to Sector.CeilSlope to match their names with similar sector properties.

Linedef Edit Form, UDMF: added less annoying warning about missing activation flags (no checks if an action actually requires activation yet...)