move rcloud.r & rcloud.python into rcloud.packages
fix ace.require that got lost during rebase of feature-langs
remove "yet!"

it was an in-joke and it reads funny with "in this deployment"
whitespace
use RCloud.language for scratchpad mode
set language mode for command prompt; massive command prompt refactor

fixes #1105
the command prompt code was a horrible, horrible mess, with the history
and command entry code within methods of the prompt. legacy of the push to 1.0

build history and entry in private methods the way we are doing elsewhere
add a bunch of private members
have sensible methods and propagation for the language

it makes a lot more sense, to me anyway.
initialize language list within command prompt
use usual "class pattern" in RCloud.language

the "local variables pattern" is okay, but this is a little more expressive
enable immediate switching of cell language mode

also remove unused languages list