Fix build

Interesting project, this is!

I just had a quick look at the code and tried to build it in LCPXpresso. These were the changes I needed to get it compiled...

- adding -std=gnu99 compiler flag
- replacing `#include "lpc214x.h"` with `#include "LPC214x.h"` in most c-files.

I also added an ignore for the build directory...