Refactoring length() in LineInformation to regionLength() + fixed 2 exception

getLength() in LineInformation returning only part of the line wasn't very intuitive, so now it returns the length of the whole line with delimiter. I kept the old functionality in method getRegionLength() for backward compatibility.
The method getEndOffset() now returns the last position in the line (including delimiter). This is mostly backward compatible, the only difference is that the old method could return offset outside of the editor range if we were querying information about the last line.
I also fixed two exceptions, which were thrown on ParagraphMotion and SentenceMotion if we were on the last line.