Use a new splash screen which begs for donations.

Logo GIMP image file and ppm added to managementtools/
as DonationSplash.[xcf/ppm]. WelcomeSplash.ppm updated.

License.txt contains attribution to gratipay.com and
explanation why we can use their logo in our splash
screen.

-> First v3.0.12 release "Random acts of kindness"
   is ready for release.
Base/OSX: Mark only OSX 10.9 as supported.

Only report OSX 10.9 Mavericks as supported, as we no longer
officially support OSX 10.8. OSX 10.10 isn't out yet in a
final release and PTB isn't tested with it in any way, so
we don't declare it supported/tested yet.

-> Only code change in PsychSupportStatus()

-> Also a billion white-space and indentation cleanups all
   over the file.