DocumentManager: Handle 0 pointers gracefully

Change-Id: I26be412414d55963456941c9cb1aac2c7db5aee9
Reviewed-by: Eike Ziller <eike.ziller@digia.com>
FakeVim: Support for relative line numbering

Settable using 'relativenumber' and 'rnu' options.

Change-Id: Idb5aa9669bdfa157d6bb6b517a09d63e8f511b95
Reviewed-by: hjk <hjk121@nokiamail.com>