vimode: Handle folded lines correctly

[techee]

This PR addresses some issues of the plugin with folded lines - see the individual commits.

I'd also like to automatically set the cursor position when a block gets folded to be set on the visible line (and not hidden somewhere inside the fold) but right now I don't know how to correctly react to the fold events - see https://sourceforge.net/p/scintilla/bugs/2438/

@scresto09 Do the changes look OK to you and does the plugin behave correctly with them?

[scresto09]

Hello,

After read the https://sourceforge.net/p/scintilla/bugs/2438/ report, I think the best way to automatically set the cursor position on the visible line is surely to track the SCN_MARGINCLICK event.

I did some modification to handle this with the commit 5608b74 in pull request #1326

What do you think about this ? Thanks

[scresto09]

It seems there are some issues with the changes in commit 907b9bc, for example the cursor can no longer go up to the first line, or when some lines wrap.

I've made some changes to try and fix this with the commit 274ff97 . What do you think about this ? Thanks

[scresto09]

OK, it works fine, thanks

[scresto09]

I just create #1349 for SCN_MARGINCLICK part.