Big oversight in my previous commits: Widgets need to be able to have
specific configurations (i.e. the path for different instances of the
"disk" module has to be different).
To account for that, it is now possible to assign an "alias" to a module
instance using ":" (for example: -m "disk:home"). This alias is then
used for the configuration parameter resolution automatically, for
example:
-m disk:home -p home.path=/home
As a consequence, parameter names in the module code are now relative to
the module, which means: shorter!
Allow the user to specify arbitrary configuration parameters from the
commandline and evaluate those in the modules (and elsewhere). Re-enable
the CPU module as a first showcase of this functionality.
Allow theme entries to be lists that are then iterated. For this
purpose, extend the Config class so that it can serve as generic store
for data items. That makes it easy to centralize code used for rotation
etc. in a single place.
