Replacing multiple selections with newline

Replacing multiple selections with newline results in odd behavior. All selected text will be removed, while the new line will be added only at the main caret position.

This should be handled in one of these two ways:

1. Remove all selected text and insert newline at every caret position. This will make the behavior consistent with how pressing backspace over multiple selections behaves in Scintilla (but not like in Word).
2. Remove only text from main selection and insert new line only at main caret position. This will make the behavior consistent with Word (but it will not be analog to the behavior of backspace in Scintilla).