Following up on #3231

Apply `constrain`, `NOMORE`, `NOLESS` and `CRITICAL_SECTION` macros
wherever possible.

Keep "astyled" reformatting

Apply `ENABLED` / `DISABLED` macros to files needing only a small
number of changes.

Just set up the pin. Don't move to a random position.

Simplify servo::move()
* servo::move() does not need the pin parameter - The pin is set during servo_init() with attach().
* servo::move() does not need a return value.

SERVO_LEVELING is the wrong condition to deactivate the servos.

Remove some temporary (Servo *) variables.
SanityCheck for the servo indexes.

Assuming #2470 fixed up the main issue.

- Have `Servo::attach` explicitly return -1 if it fails
- Check for -1 in `Servo::move` because `servoIndex` might be 0
- Make `attach` / `detach` calls conditional on `SERVO_LEVELING`
- Move `SERVO_LEVELING` define to `Conditionals.h`

as sugested by @c-born
inhttps://github.com/MarlinFirmware/Marlin/issues/1885#issuecomment-92618240

move(pin, angel) - Sequence of attach(pin), write(angel),
                   if DEACTIVATE_SERVOS_AFTER_MOVE is defined waits SERVO_DEACTIVATION_DELAY, than detaches.

As we have jitter on the servos during moves of the steppers, and detaching them improves this behaviour,
the usual sequence to handle a servo movement is:
attach(pin)
write(angel)
delay(until the servo finished the move)
detache()

Here a function to handle the complete sequence.

Servo.cpp and Servo.h were changed to lowercase in Makefile but not their actual filenames.

Updated "servo.h" to "Servo.h"

Formatting for code-folding plus minor style changes to less active
code.

Changed AUTO_BED_LEVELING to AUTO_BED_COMPENSATION

Check the Readme for instruction how to enable and configure the feature

Diffed and merged, preserving my updates

Integrated fixes from henrikbrixandersen pull request #504