Kwargs are passed as pyplot options

Getattr allows pyplot to have options dynamically passed to it.
Isinstance processes arguments passed into phylo draw in ways
appropriate to the data types used in them.
Added linecollection for clade lines option

An option is added that allows clade lines to be created with
matplotlib's linecollection objects.  The linecollection objects are
stored in tuples that are added to the pyplot plot.
Added changes based on feedback from @etal

Fixed spelling error, line size, and comment location.
Added exception catching for the format of user entered pyplot options key word
arguments.
Changed global to local object scope in the objects containing the plot line
collections.
Redundant error catching removed from  matplotlib.collections import.
Additional comment added to draw_clade_lines.
Removed test printing line and changed exception test try statement to have
better syntax.
Phylo.draw: edited docstring & made the printed error message a ValueError

Stripped some spurious whitespace.
Phylo.draw: rename local variables for PEP8 compliance

Removed unnecessary line continuations (end-of-line backslashes inside parens)