Add alias for uerrno so the user doesn't have to know about the
CircuitPython special names for the module.
Make os and time weak modules (aliases) making it possible to add
functionality to those modules written in python.
Example:
'import os' will now look in the path for an os module and if not found
it will import the builtin module. An os module written in python will
import the builtin module through its name prefixed with an underscore
(_os) following the C module naming practice in CPython.
Also right align the macro values to increase readability making it
easier to compare the values for samd21 and samd51. Even the longest
macro from py/mpconfig.h will fit with this alignment.
cec9a69a15