Gutter sizing (again)

[ProgerXP]

Previously implemented: #206 #222

Issues:

• some commands shrink the gutter; I have found at least Ctrl+Alt+I - why?
• Ctrl+D (duplicate line) should refresh the width like other editing commands do

[cshnik]

• some commands shrink the gutter; I have found at least Ctrl+Alt+I - why?

It uses SCI_CLEAR command which internally uses previously implemented update of gutter width (document is empty at the moment). This caused specified behavior.
Fixed Ctrl+Alt+I behavior: gutter update added for SCI_ADDTEXT command handler.

• Ctrl+D (duplicate line) should refresh the width like other editing commands do

Fixed.