Fixed errors related to the latest Rust
Fixed the tests code with regards to P/Gc pointers
Excluded broken lpc17xx demoes from Rakefile
Merge pull request #189 from kvark/rust

Fixed errors related to the latest Rust
ioreg::test: Test gap offset
ioreg: Fix incorrect calculation of gaps
Merge pull request #191 from bgamari/ioreg-fixes

A few ioreg! fixes
k20::{sim, pin}: Port to ioregs!
k20::uart: Port to ioregs!
k20::sim: Export regs
k20::uart: Make UART naming consistent with documentation
k20::uart: Enable transmission/reception in set_mode