Ticket #3119: fix format paragrap formatting.

(word_start): remove extra decrement.

Signed-off-by: Andrew Borodin <aborodin@vmail.ru>
(format_paragraph): fix wrong refactoring.

Partially revert of 253d27b1a347ad0376b943d8c58ed126c7e8b72f.

Signed-off-by: Andrew Borodin <aborodin@vmail.ru>
Add editor_stop_format_chars ini option.

This option contains a set of characters to stop paragraph formatting.
If one of those characters is found in the begin of line, that line and
all following lines of paragraph will be untouched. Default value is
"-+*\,.;:&>".

Signed-off-by: Andrew Borodin <aborodin@vmail.ru>
Merge branch '3119_format_paragraph'

* 3119_format_paragraph:
  Add editor_stop_format_chars ini option.
  (format_paragraph): fix wrong refactoring.
  Ticket #3119: fix format paragrap formatting.