ENH: Use fh attribute to access PyTables file
BUG: Render plot only if source provided
ENH: Created filter mixin for channel filtering
ENH: Added get_items method to AbstractParadigm

Returns current value of all paradigm variables in instance.
ENH: StopIteration now terminates experiment

Added option for Expression generators to raise a StopIteration to end the
experiment.  Sequences (e.g. `ascending`) now have a cycles argument that
indicate the number of cycles to go through.
ENH: Add current context view to AbstractExperiment
CLN: PEP8 fixes and fixed references to *.channel