FakeVim: Use registers 0, 1 and -

Command "y" additionally yanks text to register 0 if the default
register " is used.

Delete and change command set register 1, if removed text contains
multiple lines, or to small delete register (-).

Register " is always set.

Change-Id: I9d357911cedaac97fb1a91698523c9b0f3de8621
Reviewed-by: hjk <hjk121@nokiamail.com>