xah-smart-delete related fixes and improved customization

[maxwestrom]

• Fixed the bug where brackets with prefix characters would not be properly deleted (solves issue #167)

• Added optional parameter DeletePrefix to the following functions:

xah-delete-backward-bracket-text xah-delete-backward-bracket-pair xah-delete-bracket-text-backward

If DeletePrefix is non-nil, also delete any prefix characters before the opening bracket.

• Fixed the bug where `xah-smart-delete' fails to delete an unbalanced bracket

• Added the ability to dispatch xah-smart-delete default behavior by setting xah-smart-delete-dispatch:

If the Alist contains a value pair of the form (default . ‹function-name›) Then that function replaces the `xah-smart-delete' default behavior.

• IMPORTANT: The following code from `xah-smart-delete' was moved to after the dispatch call in order to make the behavior fully customizable. This probably means it will have to be added to xah-wolfram-smart-delete-backward and xah-html-smart-delete-backward or they will lose this functionality:

((region-active-p) (delete-region (region-beginning) (region-end))) ;; 32 is space, 9 is tab, 10 is linefeed ((eq (char-before) 32) (while (eq (char-before) 32) (delete-char -1))) ((eq (char-before) 9) (while (eq (char-before) 9) (delete-char -1))) ((eq (char-before) 10) (while (eq (char-before) 10) (delete-char -1)))

• Updated docstrings and version dates for all functions and variables changed.