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.

Bio/Phylo/_utils.py

@@ -421,5 +421,15 @@ def draw_clade(clade, x_start, color, lw):
     # Also invert the y-axis (origin at the top)
     # Add a small vertical margin, but avoid including 0 and N+1 on the y axis
     axes.set_ylim(max(y_posns.itervalues()) + 0.8, 0.2)
+    """"Keyword arguments passed into this method are accessed as pyplot options.  The input format should be:
+        PyPlotOption=(tuple), PyPlotOption=(tuple, dict), or PyPlotOption=(dict)
+        For example: Phylo.draw(tree, axhspan=((0.25, 7.75), {'facecolor':'0.5'}), axvline={'x':'0', 'ymin':'0', 'ymax':'1'})"""
+    for key, value in kwargs.iteritems():
+        if isinstance(value, dict):
+            getattr(plt, str(key))(**dict(value))
+        elif not (isinstance(value[0], tuple)):
+            getattr(plt, str(key))(*value)
+        elif (isinstance(value[0], tuple)):
+            getattr(plt, str(key))(*value[0], **dict(value[1]))    
     if do_show:
         plt.show()