Remove remnants of unused (renamed) XML tags.

Remove remnants of unused (renamed) XML tags.
```
FixDoubleDashs
FixDoubleGreaterThans
FixEllipsesStarts
FixMissingOpenBrackets
FixMusicNotations
```
Those 5 have been renamed (`s/s$//`), apparently serving no more purpose.

Also fixes a couple of typos.