Reworked the module system

Combined the player & poll modules into one module, now called progress
(that name will surely change). It now covers the both old player’s and
the old poller’s responsibilities. Forcing an interface between the two
was awkward, and created more trouble than it was worth.
Renamed new progress module to play

Also deleted old play & poll modules, and capitalized first letters of
command descriptions
Naming changes in config module
Renamed progress module (Part II)