Some letters do not work in letter tablature entry mode (opposed to number entry mode)

- The current default setup for shortcut keys has a conflict between the 'H' assigned to the hairpin and the 'H' assigned to the 8th fret in tablature letter mode.
- There are defined tablature note entry actions only up to the 9th fret.

Fixes:

According to the suggestions in forum post http://musescore.org/en/node/25244, this patch implements the following fixes:

- Default shortcut key for haipin are changed into the more language-independent keys '>' and '<'.
- Actions for fret 10th - 14th are added, so they appear in the shortcut preference dlg box.
- No key is defined for these new actions (for analogy, they should be mapped to 'L' to 'P'), to avoid occupying several more letter keys in the general setup (note that 'N' and 'P' are already taken): the interested user has a known and simple way to define his own, if he has the need.
Merge pull request #829 from mgavioli/Fix_entering_letters_in_tablatures

Some letters do not work in letter tablature entry mode
fix #25360
fix #25231
Fix #22917 - Previous fix actually disable precise dragging of bar line grips.

When editing is exited, an (extra?) final call to BarLine::endEditDrag() is made **after** the last drag: it was finding shiftDrag turned off by the last call and forced the bar line extrema to coarse precision.
See http://musescore.org/en/node/22917#comment-99269

Fixes:
- resetting shiftDrag moved from endEditDrag() to endEdit();
- added a test at the beginning of endEditDrag() skipping it, if there is no drag.

Also fixed:
- a test for shiftDrag swapped with !shiftDrag
- an assumption that staves always have 5 lines.
Merge pull request #836 from mgavioli/fix_22917_regression_in_previous_fix

Fix #22917 - Previous fix actually disable precise bar line editing