Port matcher to on_action API.
Remove code duplication.
Fix style.
Fix fix style.
Fix find_matches call in matcher:matchlist.
Fix computation in matcher of a match spanning a given 'row|col' pair
when 'row' is not the first row of the corresponding logical line.
Minor cleanup and changes to matcher.
Remove unused variable.
Fix typo.
Define $off also when $col is 0.
Indent.
Add 'matcher:select' mode.
Fix sequence generation for Shift + F1 - F10.