Deal with _anytrait_changed handlers

[aaronayres35]

Problem Description
In many cases in chaco we have _anytrait_changed methods which define a list of traits of actual interest, checks if the changed trait is in that list, and then calls a certain method. For example:

chaco/chaco/axis.py

Lines 781 to 816 in c758a65

	def _anytrait_changed(self, name, old, new):
	"""For every trait that defines a visual attribute
	we just call _invalidate() when a change is made.
	"""
	invalidate_traits = [
	"title_font",
	"title_spacing",
	"title_color",
	"title_angle",
	"tick_weight",
	"tick_color",
	"tick_label_font",
	"tick_label_color",
	"tick_label_rotate_angle",
	"tick_label_alignment",
	"tick_label_margin",
	"tick_label_offset",
	"tick_label_position",
	"tick_label_formatter",
	"tick_in",
	"tick_out",
	"tick_visible",
	"tick_interval",
	"tick_generator",
	"orientation",
	"origin",
	"axis_line_visible",
	"axis_line_color",
	"axis_line_weight",
	"axis_line_style",
	"small_haxis_style",
	"ensure_labels_bounded",
	"ensure_ticks_bounded",
	]
	if name in invalidate_traits:
	self._invalidate()

This is a case where we would want to use metadata in the trait definition and listen based on that. Similar to the recently added requires_redraw (see PR #585 and issue #595)