Added [ and ] shortcuts for changing the BMP brush size.
Added BuildingPropertiesDialog and building exterior grime.

Rooms already had interior floor- and wall-grime.  But there was no way to
place grime on the outside of buildings except for painting grime tiles by
hand.

Buildings now have a GrimeWall tile.

The BuildingPreferencesDialog allows the user to change the tiles assigned
to the a building (including exterior wall, roof tiles, etc).

Fixed a bug that checked if a room had a GrimeFloor tile when it should have
checked for GrimeWall.
Fixed off-by-1 feedback when resizing wall objects.
Made AbstractTool disabled by default.

Noticed that when starting TileZed with no open documents, all the tools
are enabled.
Added "grime" flag to furniture objects to enable/disable grime.

Automatically-placed grime should not appear in some places, such as on
open garage doors.  A new checkbox in the BuildingTilesDialog allows the
"grime" flag to be toggled on selected furniture tiles.
Added "Grime..." command to BuildingEd's Building menu.

This is a shortcut for choosing Building > Properties > "Grime - Wall".
Updated building *.txt files.
WORLDED and Q_UNUSED ftw.