Rename DownloadAdditionsForNeuroDebian.m into DownloadAdditionsForLinux.m

Also update the online help text and status output to reflect that
this script is no longer needed as a post-install step for the
packages from NeuroDebian. It is only needed if one installed
outdated packages from mainstream Linux distributions like, e.g.,
Ubuntu 12.10 and Ubuntu 13.04, which don't ship the -nonfree addon
packages and matlab-psychtoolbox-3 packages yet.

Some robustness improvements, e.g., download latest revisions of
files if revision number can't be extracted, and use textscan() instead
of textread() on recent Matlab versions, as the latter is deprecated.
Change post-installer to use javaclasspath.txt instead of classpath.txt

The masters of good software engineering and backwards compatibility
have changed the name and location of the java static class path
definition file in R2013a (v8.1) and later.

No longer shall we write to classpath.txt, but instead to javaclasspath.txt,
which can be located in the Matlab startup folder, or the users preference
folder.

Adapt: On v8.1+ we try to find the javaclasspath.txt file. If we can't
we assume it is in the users local preference folder (which we create if
it doesn't already exist) and set the path and filename accordingly.

On earlier versions, we still use classpath.txt as in the past.

PsychtoolboxPostInstallRoutine and DownloadAdditionsForLinux updated.

-> This change is entirely untested due to lack of R2013a access.
PsychLinuxConfiguration: Add 'dialout' requirement for serial port access.

Users must be members of Unix 'dialout' group to access serial ports
or devices which pretend to be serial ports.
Add protection against batch delete via Screen('Close') to internal functions.

Use the new 'specialflags' 32 setting for 'Openoffscreenwindow' and 'Maketexture'
when appropriate to protect windows and textures against accidental deletion
by usercode when it calls Screen('Close') to close its own textures, e.g., at
end of a trial/block etc.

This is to protect windows internal to PTB functions which must persist
during a session and which are hidden from / unknown to usercode, e.g.,
overlay windows for the Bits+/Bits#/Datapixx etc., renderbuffers for
the morpher and other gpgpu functions, ...