Blender Git Loki

SCons updates
* Default build dir is now: ../build/<platform>/
with <platform> ofcourse the platform you're building on.
This option is still configurable in config.opts. It was just a feature
request.
* Allow the user to specify a different config.opts file from the command
line. This one was at my todo, but Kester was kind enough to implement this
in Tuhopuu2 already. Thanks Kester!
To generate/use a different options file:
scons CONFIG=your_config_options_file