Blender Git Loki

Orange: Yet another day of file reading & library linking code...
Finally (after 10 years!) fixed the issue that was marked in a comment in
the top of the readfile.c... when using multiple library files at once,
the code that tries to map old to new pointers could fail when accidentally
pointers (in different files) had same old values.

Current code now uses proper lookup tables per open library file.
Last issues to solve;

- pointer tables still suffer the 'accidental pointer' error when linking
multiple levels of library deep, with recursive back linking to higher
levels... (I know is stupid, but should be solved!)

- The code for relative paths doesnt work for multiple levels, when the
files use different relative paths.