Start work on icode generation for classes
Generate icode for method calls

Only simple method calls with a statically typed receiver are supported.
Include binding and type info in generated code

This is only a partial fix. Test cases will be added separately.

The changes to transform test cases are mysterious, but they do not
seem to have any bad effects.
Generate icode for data attribute access

Also generate implicit attribute accessor methods.
Generate icode for object construction

Only default __init__ is supported.
Generate icode for calling __init__
Test case restructuring
Generate icode that initializes data attributes