Also contains raw memory read/write functions, read8, read16, read32,
write8, write16, write32. Can now do:
stm.write16(stm.GPIOA + stm.GPIO_BSRRL, 1 << 13)
This turns on the red LED.
With the new constant folding, the above constants for the GPIO address
are actually compiled to constants (and the addition done) at compile
time. For viper code and inline assembler, this optimisation will make
a big difference. In the inline assembler, using these constants would
not be possible without this constant folding.
Finishes addressing issue #424.
In the end this was a very neat refactor that now makes things a lot
more consistent across the py code base. It allowed some
simplifications in certain places, now that everything is a dict object.
Also converted builtins tables to dictionaries. This will be useful
when we need to turn builtins into a proper module.
