Interrupts: enable interrupt mask
core: add NULL definition
zpu20: fix timers, enhance implementation
Timer: add timer callback examples
More timer changes
Add uintptr_t and intptr_t
Improve Arduino API conformance: Add noInterrupts() and interrupts()
Improve Arduino API conformance: Add random(long), randomSeed(long), etc.  This PRNG is based on the ancient Berkeley source.
Merge pull request #12 from DaveAckley/master

Improve Arduino API conformance
Merge branch 'master' of github.com:alvieboy/ZPUino
Clear .bss
Merge pull request #11 from GadgetFactory/master

Fix for AVR8 Makefile and 2.0.4 release
Merge pull request #13 from DaveAckley/master

Clear .bss
Merge branch 'master' of github.com:alvieboy/ZPUino
device registry: fix returned index for PPS
zpuino: use C standard for normal C calls, add some defines for MAX/MIN
Add SPI library
Add preliminary GPIO
serial: Add RX+TX for serial
Add SPI library for 1.0, do some small fixed