hard uart now returns int8_t rather than int
switched to xc8 headers
update system file to include freq in MHz as well as Hz
default uart is now defined in uart.h, saves having a copy in every makefile
hard uart now returns int8_t rather than int's. (this belongs with earlier commit about this
bring in new irq handling and systimer which is built off generic timer. gitignore ignores doprnt which is generated by xc8 when including sprintf. main runs usb hid as before but now also includes a systimer check to switch LED at one second intervals. LED seems to switch at closer to 0.7s