Pass a final boolean argument to TerrainBlock::import to control
y-axis flipping. It is enabled by default, since this was the previous
default behavior.
This should be added as an option in the terrain import dialog - see
game/tools/worldEditor/gui/guiTerrainImportGui.gui
- displaySplashWindow() now takes an optional path to a bitmap file.
- Missing, unavailable and warning texture paths now come from
GFXTextureManager static methods.