Add support for calling constructors on abstract types #14
Description
Calling constructors on abstract types is necessary when extending an abstract type from C#.
Right now they are skipped by the module definition generator since that's how it was in the prototype. Not sure if I did this because I wasn't thinking about extending abstract types from C# or if I was just trying to avoid dealing with them at the time. Either way, we need a strategy for calling inline constructors on abstract types, which will be trickier than with concrete inline constructors.