Improved experiment.List for multiple fitting

API allows .call() and .get() which calls a method or gets an
attribute on all the experiments in the List.

This enables .fitHandles() and .fitRip() to work on all experimetns
in List simultaneously, vastly improving analysis throughput.
Fit() can now take fitfunc with no defaults if all parameters are specified as kwargs
Updated tests to experiment to reflect List improvements
fplot.plot now plots only FEC curves when given TrapData