Inconsistent use of 'real'

[jcrist]

Datashape has 3 things using the word "real" in them:

• ds.predicates.isreal: checks if the datashape is floating point
• ds.real: alias for ctype("float64")
• ds.typesets.real: contains all numeric, non-complex types

This is inconsistent, and should be corrected. I'd prefer to make ds.predicates.isreal check for containment in ds.typesets.real (expanding isreal to return True for integers). Removing the alias may or may not be beneficial.