tkdiff Code

Work on Aqua UI some more. Reworked the Merge window a little so that the frames are properly configurable.

Remove aqua UI workarounds that are no longer needed and now just mess things up

(More) Minor behavioral refinements addressed
- Remaining Save-file-browsers now honor user "directory interactions"
- Button-2 jump scrolling has been incorporated when over the Map
- Cmdline diff-options w/blanks can now be effectively passed through
- Help info on cmdline quoting rules added, per diff-options chg

Minor behavioral, and internal style/comprehesion refinements
- Vastly simplified prior chg involving merge choice tagging
- Split/Combine adjustment arrow buttons now auto-repeat
- Replaced unintended use of <tab> characters

Added new features in the Merge Preview window
- Now displays line numbers whenever other windows are requested to do so.
- Also always displays meta-data indicator marks as to which main window
(left/right) contributed its diff region content into the merge.
- text tagging precedence is now implicit and no longer needs 'adjusting'

Merge output SaveAs browser now correctly responds to directory traversals

Repaired one bug, and two oversights affecting general usage scenarios
- Eliminated default <CR> to <NL> input conversions causing crashes/missing-hunks
- Wheel-scrolling now works when over the MAP (it targets the 'active' window)
- Cmdline outputfile naming is now cancelled if/when multi-file support is active.
Accordingly, an ellipsis (...) now dynamically appends to pertinent GUI elements
to hint pgm WILL prompt (or not) for the filename as the situation requires.

Fixed a Split/Combine corner case causing key internal data to be shifted
- hunks beyond the CDR were shifted if the amount of padding was changed
- inline tagging now uses a base/displacemnt method to avoid ANY shift

Resolving small inconsistencies in startup behavior and messages
- add/align extra failure msgs regarding insufficeint items to compare
- reduce confusion (int/ext-ernal) about when newDiffDialog appears
- simpler solution to earlier (-r103) fix (avoiding 'string cat' use)
- increase 'package requires tk' to minimum version of 8.5
- add missing 'update-display' call if startup yeilds zero diffs

Use join instead of string cat, to preserve compatibility with wish 8.5