Issue19 clean up code

This is a major code clean up to address issue #19.
The package Annex60.Media has been redesigned (but further refinements are proposed in #21.
The revision of the Media package also fixes #16.
File permissions have been corrected, as previously, some .mo files had the executable flag set.
To some package, a graphic has been added to the icon as is done in MSL 3.2.1.
All unit tests run successfully.