Simplify setRaspberryVersion function and fix possible bug where pin schema could be reset
Simplify more internal function interfaces by giving them scope access to module state
Clean up some variable naming
Bump to v0.3.4
Improve coverage and clean up tests around pin translation under various hardware revisions
Add API documentation to readme and try to make it more understandable generally
Remove error callback that makes no sense
Return error if attempting to write to a pin that has been set up for input
Bump to v0.4.0