The only real differences between these generators is the file extension
and the templates themselves. We can uses a shared abstract class
with a few abstract properties to provide all of this to the same base
class. This results in less code duplication and easier maintanence.
I've made a few cleanups to the shared template:
- use `str.capitalize()` instead of `str.upper()[0] + str[1:]`
- use `open` as a context manager
- use f-strings
- put some duplicate calculations in the initializer
D lang compilers have an option -release (or similar) which turns off
asserts, contracts, and other runtime type checking. This patch wires
that up to the b_ndebug flag.
Fixes#7082