Allow to set the source epoch of the build with
PROJECT_VERSION_TIMESTAMP.
When unset fetch the commit timestamp of the current HEAD automatically
instead of leaving the source as 0.
We have no use for this on the MMU, but it doesn't hurt to follow what
we do on the MK3.
Substitute documentation to reference AvrGcc by default, which locks gcc
to the dependency folder.
AnyAvrGcc is inteded to use any system/external gcc version (as the name
implies).
Remove fixed version in AnyAvrGcc.cmake
Update build.py to use current avr-gcc version defined in bootstrap.py
Attempt to change MM-control-01.hex to MMU2SR-<project version> like in buddy releases