Changed Pin Assignment for the RAMPS motherboard so that LCD and Rotary encoder are all wired to AUX-4

This simplifies wiring for those with RAMPS 1.3 and 1.4 boards.
Fixed type in e-jerk
While Waiting for hotbed to warm up via M190, LCD Display and Click Encoder input freeze until target temperature is reached.
Merge pull request #100 from tommycheng/patch-1

While Waiting for hotbed to warm up via M190, LCD Display and Click Enco...
Add create_speed_lookup
stepper: Clarify comment on timer-counter configuration
Add instructions to regenerate speed_lookuptable when changing F_CPU
Added PID autotune. (experimental)
M303 Starts autotune. Wait till the Kp Ki and Kd constants are printed.
Put these values in Configuration.h
Merge branch 'Marlin_v1' of github.com:ErikZalm/Marlin into Marlin_v1
Corrected active_extruder when autotemp is used.
Added FAN_PIN -1 checks
Removed !!!. Stupid arduino bootloader can't handle this.
Fixed typo
Do not disable steppers when there are moves in the queue.
Added CONTROLLERFAN.  (Controlling a fan to cool down the steppper drivers)
Merge pull request #106 from bgamari/Marlin_v1

Make F_CPU dependence of stepper.cpp more explicit
Added 20MHz support.
Merge pull request #99 from Justblair/master

Better pin configuration for rotary encoder in RAMPS boards
Added more manage_inactivity checks
Merge branch 'Marlin_v1' of github.com:ErikZalm/Marlin into Marlin_v1