Fix: Not working when multiple views opened

[lordfanger]

I've found it not work well when I split view and maybe when I open new window. Summary:

• Added watching after each created window (I hope it is OK).
• Unregistered event listener for LayoutChanged after view closed. Don't know if it hurt anything. Probably the event will never be fired after view close anyway.
• Added overflow for start/end in OnSettingsSaved() (or was it intentional to not count the overflow there?)
• Visible start and end are counted from min/max of what is visible on each view. Possibly can be processed whole file when one view is at start and other at end.
• Fixed bug in IsAboveChange() - was not counting above change but above visible (and carets could write text outside visible area)

[madskristensen]

Awesome. Thank you!

[lordfanger]

That was pretty fast. :)