Refactor of Adafruit_Floppy for timer support & mac disk success!

OK we were still having some issues with mac 400k/800k floppies and their weirdly long GCR pulses so we decided to refactor our bitbanging code to use a timer capture peripheral and a pwm waveform generator (bit odd because the period is what changes there, but it is possible with most timer peripherals) We also characterized a pile of floppy drives we had - still best results came from the Sony MPF but a few other drives were able to read with 10+ (!) retries. The timer refactor didn't seem to make much difference on the GCR decoding but it seemed like the right thing to do and there's less fudge-factor dependancies on the cpu clock frequency. Also, FLOPPY SOCKS! #adafruit #floppy #retro Visit the Adafruit shop online - http://www.adafruit.com ----------------------------------------- LIVE CHAT IS HERE! http://adafru.it/discord Adafruit on Instagram: https://www.instagram.com/adafruit Subscribe to Adafruit on YouTube: http://adafru.it/subscribe New tutorials on the Adafruit Learning System: http://learn.adafruit.com/ -----------------------------------------