Blender Git Loki

* Made BLI_join_dirfile() check before adding a slash between dir and file so as not to get /foo///bar.blend
* Pointcache now uses the process id to construct the path for unsaved files. (so 2 or more blender's open wont try to read/write the same pointcache)
* Temp pointcache is cleared when existing blender, added BIF_clear_tempfiles() for this. Should also be usedto clear EXR's in the temp dir (TODO), BIF_clear_tempfiles also needs to be added in more places. (On file load for instace)