Partly-complete implementation of DescribeTypeJSON

Includes support for interfaces and variables, accessors and some fields of methods, including their associated metadata.

Doesn't include support for class-level interfaces and inherited properties.
Mostly-complete implementation of DescribeTypeJSON

Adds support for bases and method parameters, the 'declaredBy' field and for coIlecting inherited properties.

Class-level stuff still missing
Finish implementation of DescribeTypeJSON

Adds support for the class's own metadata and includes some code cleanup. Not enough, but something.
Merge pull request #241 from tschneidereit/master

Complete DescribeTypeJSON implementation