Draft: Dynamic Clock Speed#5

Draft

dwbrite wants to merge 3 commits intoirevoire:masterfrom

dwbrite:feat/dynamic-mcg-modes

Commits on Feb 20, 2020

use `crate::` instead of `teensy::` in port macros
Devin Brite
committed
(wip) support setting the clock at runtime
Devin Brite
committed
add data section to linker script for dynamic clocks
Devin Brite
committed