Add Regex and Range properties
Implement Color property in terms of Enum, Regex, Range and Tuple
Restore "1 2 3" syntax in DashPattern using Regex
Make Tuple and Either raise TypeError consistently with other classes
Fix bokeh/tests/test_properties.py
Make bokeh/tests/test_properties.py easier to read
Simplify Enum's constructor, use enums.enumeration()
Make sure that enumeration items are unique
Don't allow empty tuple to Tuple(T1, ..., Tn)
Add preliminary systematic tests of properties