Default behavior is the same as before, but now a user may selectively disable some commands.
Also: deleted the mappings for import.vim.
Tested: by trying the commands for fmt, import and godoc in succession to make sure they still work. Also, ran test.sh in ftplugin/go.
R=golang-dev, dsymonds
CC=golang-dev
https://golang.org/cl/10124043
Vim autocompletion respects the $GOPATH variable and does not
ignore dashes ('-'), dots ('.') and underscores ('_') like found
in many remote packages.
Environment variable $GOROOT is determined by calling
'go env GOROOT' instead of relying on the user's environment
variables.
Fixes#3876Fixes#3882
R=golang-dev, franciscossouza, dsymonds, minux.ma
CC=golang-dev
https://golang.org/cl/6443151
