reworded tooltip for Tripod Motion button; fixing spelling and making more clear

Uses the bglFlush() and is_a_really_crappy_intel_card() hacks to give
better support on low-end Macintoshes with integrated Intel graphics
chipsets. Patch received from "UncleZiev" on #blendercoders, but I
adjusted it so other video chipsets and platforms are unaffected.

The only visual difference is that on MacBook and iMac machines, the box
select outline is drawn with solid, not dashed lines like other platforms
and not invisible as they were previously.

Incorrect default value for new materials' transmissivity. Default value
should match "classic" non-transmissivity materials.

Removed -mpowerpc -mtune=G4 from several SCons files, so it will work on
either PPC or Intel architectures under OSX. These options should be
inherited properly from the rest of the OSX SCons build system.

Was crashing the import_obj script when using Python 2.3.

Python 2.4+ supports large list processing with generators, but
Python 2.3 will break if you use that syntax. Until we depend on
the newer versions, I have commented out the generator syntax and
only use the list-comprehension type instead.

Needed to add the conditional commands to ranlib for the darwin platforms.
Matches the example of the other intern/*/Makefile libraries.