Add CPC putchar to the linker file.

The default implementation uses RST 8, which is not going to work for us.
Add missing const.

* Let's optimize!
Update crt0 for current SDCC version.

* There is a new INITIALIZER/INITIALIZED system in SDCC for initializing
static variables. This must be handled from CRT0.
Implement logging.

* Must be good for something...
Include the global loader to avoid cpp warnings.

* Makes sure things are done in the right order.