fakevim: Handle completion in insert and replace modes

Text inserted without FakeVim's intervention (code completion) is
handled in insert and replace mode so that '.' command also inserts any
externally inserted text.

After movement in insert mode last command (initiated by '.') is not
cleared until new text is inserted.

Deletion in insert mode is part of dot command.

Change-Id: Ic55b3cdecaf4323e88cd321b218fae661de7a63e
Reviewed-by: hjk <qthjk@ovi.com>