Add more warnings to failed image loads. Remove unneccesary image loads.
Remove unused function argument from texture loader
The WRF file directives TEXPAGE and TCMASK are no longer needed, and are now ignored.
Instead textures are pulled in as dependencies as needed. New qtscript function
replaceTexture() allows to explicitly replace one texture with another, and this is
used to reimplement base plates depending on tileset. The kevlar vest graphics
change in alpha campaign is not yet reimplemented, as more campaign script porting is
needed first.