Made the flipped y-axis on terrain import optional.

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
Adding a basic rule-based terrain painting implementation.

http://www.garagegames.com/community/resources/view/17145
Filling out the variable names in the function prototype for autoMaterialLayers() for clarity.
Minor whitespace formatting changes (spacing) for consistency.
Some default particles now have additional defaults for their times[n] array.  This resolves some console warning spam.
Added a checkbox to the terrain import GUI and fixed a space.
Relocating the particles image directory out of art/shapes/particles to art/particles.  This should be a more logical and intuitive location.  Relevant managed particle related datablock save location defaults have been adjusted as well.
Resolve issue #163

Fixed and assert on changing material, and we now map the material to the MATMGR by name instead of type.
Set the Ryder as the default starting weapon instead of the Lurker.
Resolve issue #193 - Gui Editor treeview now refreshes correctly when changed through a drag/drop operation.
Remove unused OOBSign from PlayGui
Moved teleporter related particle data out of the managed data file and into art/datablock/teleporter.cs.  I also corrected a bad filepath that would prevent mission loading.
Removing the old TGE era "Buggy" vehicle.
Moving the light related assets and data out of the core.
Relocating sky related assets.

Also reduced duplication of the "empty" solid color sky cubemaps.
Relocate water related assets.

Also remove duplication, favoring DDS over other formats.
Relocate default road & path assets.
Removing the Armor script class.

Using PlayerData as the generic namespace.  This is more inline with other default datablock methods.
Fix for issue #282

Material selector now renders preview thumbnails.
Update README.md
Cleanup of weapon fx and assets.

This reduces duplication by grouping assets used by multiple weapons in one location: shared.
This reduces duplication and cleans particle fx that was spread across multiple files.  We now have rocketfx.cs and grenadefx.cs
This also fixes some minor particle fx console warnings/errors.
Fixed missing material for Cheetah Turret.