runCommand -package:structured-cli -package:github-release -package:process -package:shake -package:mongoDB -package:options -package:cabal-install -package:pandoc-plot -package:quickcheck-state-machine is:exact -package:graphviz -package:io-streams -package:hledger -package:libmpd

Run a Command.
Given a list of command/action pairs, prompt the user to choose a command using dmenu and return the corresponding action.