make stringIterator aware of newlines
check if op.lines is in sync with atext-newlines

Conflicts:
	src/static/js/Changeset.js
op is ok, if it doesnt include newlines. op is ok, if op.lines is equal to newlines in op.chars
Merge pull request #2405 from webzwo0i/fix-lineassembler-not-finished

Fix lineassembler not finished