#1554 desktop and appstream metadata improvements

[Stuart Prescott]

Hi!

The attached sequence of patches updates the .desktop and appstream metadata files to the most recent versions of the specification plus offers some additional tweaks based on user feedback.

fix-mime-types.patch:

we had grumblings that rosegarden was telling the file manager that it could open wav and mp3 files but it's unlikely that is what a user really wants to do, so removing these offerings from the mime info seemed appropriate.

desktop-file.patch:

The existing file lacks a Keywords vaue which is good practice for discoverability. The newest version of the spec also insists that the filename (which is the Id of the desktop file) should be in reverse-dns format (tld.domain.application): com.rosegardenmusic.rosegarden. (in retrospect adding the keywords and changing the filename perhaps should have been separate patches but renaming files with patches is ugly anyway)

appdata-format.patch

The appstream metadata format has changed a lot since the original xml was written; this patch updates the file to the new format.

appdata-location.patch

The location that appstream metadata files should reside on disk has also changed and the legacy location is slowly being phased out. This patch updates the build system to install the file into the new location.

These patches apply in the above sequence although renaming a file in a patch is somewhat messy (so the final .desktop and .xml files are also attached if that is easier)

cheers
Stuart

[Ted Felix]

These have been applied as [r15125] through [r15130]. I also ran appstream-util validate and fixed the errors it identified. Those changes are in [r15131]. Please review.