misc/vim: add plugin with Fmt command.
misc/vim: add plugin with Fmt command.

Fmt command filters the current Go buffer through gofmt.
It tries to preserve cursor position and avoids replacing
the buffer with stderr output.

R=golang-dev, dsymonds, niemeyer
CC=golang-dev
http://codereview.appspot.com/4382053

Committer: David Symonds <7f6bb564ed9e580d4f0aa90d53b34578e5d24cb9@golang.org>

dsriram/golang,gnanderson/go,pombredanne/go-deleteme,dsriram/golang,ssrl/go,dsriram/golang,apparentlymart/golang,gnanderson/go,apparentlymart/golang,tv42/old-go,tv42/old-go,pombredanne/go-deleteme,apparentlymart/golang,ssrl/go,ssrl/go,pombredanne/go-deleteme,tv42/old-go,pombredanne/go-deleteme,pombredanne/go-deleteme,dsriram/golang,tv42/old-go,tv42/old-go,ssrl/go,gnanderson/go,tv42/old-go,gnanderson/go,tv42/old-go,ssrl/go,dsriram/golang,apparentlymart/golang,gnanderson/go,dsriram/golang,apparentlymart/golang,dsriram/golang,apparentlymart/golang,ssrl/go,ssrl/go,pombredanne/go-deleteme,gnanderson/go,apparentlymart/golang,pombredanne/go-deleteme,gnanderson/go