OS9 Psychtoolbox 2.55 released

Hi all

OS9 Psychtoolbox 2.55 has been released. This is a minor update, fixing
the bugs reported since the release of 2.54 on March 6. We recommend
that all users of the OS9 Psychtoolbox upgrade to this new version.
http://psychtoolbox.org/download.html#os9

Changes:
- Incorporated Frans Cornelissen's fix for a bug in AssertMex. This
fixes a bug in DescribeScreen.
- Deleted Gestalt.m from OS9 Psychtoolbox since it is superfluous to
Matlab 5's GESTALT, yet would interfere if the path places the
Psychtoolbox ahead of Matlab's toolbox, as reported by Frans
Cornelissen.
- Updated help text in Snd.
- Throughout the whole Psychtoolbox, now consistently refer to this
version as "OS9". We used to refer to it as the "Mac" version, which
has become ambiguous.