Blender Git Loki

More updates, fixes and cleanup to install_deps.sh.

So, after hours of wild hunt, I think both CMake and Scons builds work again.
There were several small issues hiding here and there, esp. for scons.

*WARNING* the --all-static is currently officially broken (it was already quite useless in fact).
I�??m seriously considering dropping it completely, having a script compiling a chain
of static libs in a complete working way for *two* different build systems is just
too much work (static libs are *really* a nightmare at link time).

Builders who want to generate static Blender (to share it e.g.) will have to handle things by hand for now.

Main other points changed:

* Many changes to generated settings for scons (notably, I had to hack around the fact that the short ld -l
option does not work with lib names like 'Iex-2_1', which is not that surprising).
* Opencollada remains the only lib built statically (can't get it to build dyn currently).
* All other libs, even ILMBase ones, are now fully dynamic ones.
* Some general cleanup with CMake definitions of built libs.
* Git-libs do not clone again and again the repo anymore!