MotionPlanner: Change return type of planner_have_commit_space() to bool.
AvrClock: Refactoring to enable hardware PWM implementation.
AvrClock: Implement hardware PWM.
PrinterMain: Move heater safe temperature checking from PWM timer ISR to control calculation event and to blinker.
This will allow using hardware PWM for heaters. It's even generally safer since the blinker event feeds the watchdog. Though the response time is a bit worse.
PrinterMain: Take invert into account for heater and fan emergency action.
Refactoring to make heater and fan PWM abstract.
This will allow writing the final glue needed to use hardware PWM.
AvrClock: Implement PWM with 16-bit timers.
aprinter-ramps13.cpp: Use hardware PWM where appropriate.
This includes moving the second fan from MegaPin5 to MegaPin11.
aprinter-melzi.cpp: Remove documentation.
It is out of date, and important stuff is supposed to be in the readme already.
aprinter-melzi.cpp: Use hardware PWM where appropriate.
Add forgotten aprinter/printer/pwm/HardPwm.h.
Add experimental Megatronics 3 port.
aprinter-megatronics3.cpp: Use own parameters for third extruders.
Not the same as for second extruder.
avr-asm-ops/sqrt_26_large.h: One cycle optimization.
avr-asm-ops/div_11_16_l15_s13.h: One cycle optimization.
avr-asm-ops/div_11_16_l15_s13.h: Fix cycle calculation.
Update README.md
MinMax: Rename functions to avoid conflicts with evil headers.
*Clock: Implement a configurable timer clearance.

This will be useful to prevent interrupt storms resulting in failures to respond to more important interrupts in time.
Enable some extra clearance for event channel timer.