This commit gets rid of the old lib/tests/other/executable.php
file completely because it was only executable under unix OSs
and moves the check to be performed against some mimetex binaries
that are known to be executable and bundled with every installation.
Note this was discovered because the weekly rolling process changed
the execution permissions of the "fixture" file and, at the end
we decided to get rid of it completely, folowing the plan above.
This patch removes deprecated PEAR excel export lib in favour of newer PHPExcel,
the ODS exporter implementation is finished and a test script is included.
The default Excel format is now 2007, file extension is changed automatically
to match excel format.