Draw Grid Mode: fixed a problem where "continuous drawing" would redraw all previously drawn shapes each time a drawing was finished. Fixes #912

UDBScript: fixed an issue where the Thing's class getSector method did not return null when the thing was not in a sector. Fixes #897

(Text labels are removed because of performance issues)

Added action to change the index of linedefs, things, sectors, and vertices. Can be accessed through a shortcut (not bound by default) or the menu of the respective mode (#903)

- A new "Show Textures" option up on the top bar, which draws any sector not flagged to be hidden on the textured automap
- Holding Shift will highlight sectors instead of lines
- Left-clicking on a highlighted sector will toggle the "Not shown on textured automap" flag
- Textures will be shown when Shift is held down even if the "Show Textures" toggle is off

Edit Selection Mode: fixed a problem where floor and ceiling textures were unintentionally scaled in UDMF when resizing the selection. Fixes #873

Nodes Viewer Mode: fixed a problem where trying to engage the mode with an empty map could crash. Fixes #857

Map Analysis Mode: fixed a problem where lines with fractional vertex positions could erroneously be reported as overlapping