Make the param version of _defaultOf for reals and imags use the default size

Suggestion from Brad.  Tested on std.
Merge branch 'master' into defaultOfRealDefault
Merge pull request #314 from lydia-duncan/defaultOfRealDefault

Default of real default [trivial]

In _defaultOf, replaces the param references to a specific size of imag and real with the default type for
maintainability.  Tested on std.