Sectors Mode: fixed a problem where dragging a single highlighted sector did not move the things in the sector when synchronized things editing was enabled

- Prevent from showing up in Custom tab
- Make sure their sectors are updated upon value changes

Added autosaving of the current map. Autosaving happens in intervals when the map is changed. It will not overwrite the current map, but rather create new files, just like backups. Autosaving interval and number of files can be configured in the "Recovery" tab of the preferences. Autosaving can also be disabled there (not recommended). Autosaves will not have their nodes built for performance reason.

3D Floor Mode: fixed a problem where the previous state of linedef arguments were not preserved for undo snapshots. Fixes #967

Script Editor: fixed a crash when the find/replace dialog was opened and the previously selected script tabs do not exist anymore. Fixes #993

Sound Propagation Mode: fixed a problem where removed sector geometry was still shown when undoing/redoing. Fixes #992

Fixed a problem where portal render style could not be set for the Eternity Engine game configuration

Visual Mode: fixed a problem where texture skewing didn't work correctly for textures scaled through sidedef properties. Fixes #985

FORCEINLINE is not a _WIN32 thing
It is a compiler attribute
use always_inline for GCC
__forceinline for MSVC
and plain inline for others

also cast glGetError via void *

clear out warnings for _WIN32 codepath

Build Win32 BuilderNative.dll with Mingw-w64

Script Editor: pressing enter in the search box now performs the search. Pressing enter in the search box of the replace tab performs a search. Pressing enter in the replace box of the replace tab now performs a replacement. Pressing the Escape key now closes the dialog. Fixes #972

Visual Mode: added support for GZDoom style texture skewing

Sound Propagation Mode: fixed a crash when things were outside the map's geometry bounding box. Fixes #975

Edit Linedef dialog (UDMF): fixed a problem where the back sidedef's controls were not disabled correctly if their UDMF fields were not set in the game configuration

Added ability to enable/disable controls in the UDMF map element editing dialogs based on UDMF fields specified in the game configurations (#953)

Visual Mode: the effect of slope things are now only applied if they are specified in the game configuration

Game Configurations: added support for enabling or disabling support for vertex heights in UDMF game configurations

Visual Mode: fixed a problem where flood selection did not work correctly when sidedefs were previously marked by other actions

UDMF type handler: fixed a problem where default values provided as integers for floating point fields failed to convert properly