Revert "Limit bedfan speed to half the full range."
Switched to 24V fan.

This reverts commit 2557c6936bfb79dbf1b1dc65b3acd831f42a162e.
Removed redundant Marlin.pde
Switched to soft PWM for bed fan.
Turn extruder fan on and off at 50C instead of having it on at all times.
New PID constants based on my own autotune settings. Turned on PID for bed header.