Accept '+' as both a prefix and a suffix, to accommodate harmony notation.

Also, added '0' (with usual suffix combination) to font and to acceptable digits.
Merge pull request #209 from mgavioli/19981_figured_bass_cross_as_prefix

Figured Bass: Accept '+' as both a prefix and a suffix
small low level optimizations
merge with head
add first tuplet regression test
update for workspaces