Replace SelectLeft/Right commands with MoveLeft/Right
Factor out commonalities between command and visual mode

This prepares the ground for operator-pending mode, since many bindings
are equivalent in command, visual, and operator-pending modes.

The numeric prefix binding is now a bit more sophisticated. If a leading
0 is entered, the binding is aborted to allow the
go-to-beginning-of-line binding to match instead.
Don't attach to .mini editors so we can ignore it key bindings selectors
Use whole words instead of initialisms per Atom's usual style
Remove redundant 's' binding
Merge pull request #182 from atom/ns-cleanup-key-bindings

Clean up key bindings