Some themers expressed desire to have translucent themes. While the current AA stuff in uLandGraphics won't really allow this to work with LandBackTex properly, seems to me it should be safe to allow alpha for LandTex. Our LandTex should all have alpha of 255 on the existing themes.

[patterns]
**.h = native
**.c = native
**.cpp = native
**.lua = native
**.txt = native
**.pas = native
**.inc = native
**.hs = native