Add way to specify types

[Wibble199]

Add a way of specifying the different types for use with the VisualProgram. Additionally, allow setting a different name for types.

For example, one could choose to create nodes for and allow a custom data type. Additionally, one could choose to ignore certain types, for example in some cases one may wish to simplify the experience and remove the int type and just allow double, but renamed as "number".

[Wibble199]

Partially complete (additional types, not renaming) with 8852558.