Add -> operator to CoTaskMemPtr

This adds the ability to get members via the -> operator.
win-dshow: Remove MPEG2 (unlikely to be used)
Add null pointer check for text file

Apparently there was no check for a null pointer file name.
Add more null pointer checks to text source
Update INSTALL for OSX 10.8
Fix crash when closing the properties window on OSX

Followup to d56432304e6e8ae00ea66bef8c1847894e5cac9f, it apparently
still crashed (on slower machines?) when closing the properties window
via mouse (by clicking the X button)
Fix path to modules in AppData
Don't require an existing datadir for modules to load
Add api to get module data and binary paths
Use qt.conf instead of hardcoded, runpath dependend, lib path
Also export plugin data destination