detaching could leave a running timer which would cause issues.
Further, detaching could truncate the last pulse causing a invalid
movement.
This change moves detaching into the ISR so it can maintain the last
pulse and not start any more timers if not needed.
Fixes issue of reentrant calls to nointerrupts()
exposed functional replacements to cli sei and SREG when dealing with
interrupts
InterruptLock class to auto stop and restore interrupt level
Fix user ISR calls to be like Arduino with interrupts disabled fully.
This exposes the Timer0
This provides a Servo library support compatible with Arduino Servo
library but only supports the two timers the esp8266 has available