Fix manifest xmls

This is a big set of changes to make all elements consistent. The big changes are

1. Consistent copyright and license text.
2. Display of description for each element and plugin - though I have not tested every validation nor tested non-element plugins.
3. Help button on each tab of multi-tab element settings.
4. Lose the extra + in repeating settings - now + at the top and - on each line.
5. Clean up of spurious files, strings etc.

This is ready to review and merge. Enjoy as there are changes to 953 files!! But they are all quite simple to read.

Oh - and the number of additions and deletions is exaggerated because my editor now strips trailing white space (at Rob's request) and there is a lot of that in the xml files I have been working on.

S