Blender Git Loki

==SCons==

* These changes bring cross-compiling Blender for Windows on Linux one step
closer to reality. The 'biggest' change is in makesdna SConscript to make
sure a linux native makesdna is built, that can be run, too. Next to that
proper checks for env['OURPLATFORM']=='linuxcross' are added in various
places.

Switch change in pluginapi.c was necessary, and AFAIK it should work like
that also on WIN32, if not, slap me.

Note: everything *compiles* now nicely, it is just that the final *linking*
doesn't work (yet). Anyone who fixes this will be the
hero of cross-compilers :)