language_de.h: updated translation and minor typos

* Added MSG_END_HOUR and MSG_END_MINUTE labels to all language files.
* Available translations:
  EN, FR, DE, ES, IT, PT, PT-BR.

Automatic selection was to unflexible.

Updated documentation

Updated language files to new logic and documentation.

Updated bdf2u8g.exe

MSG_NO_MOVE = 'Kein Zug.' > 'Motoren Eingesch.' hat mich grau Haare gekostet.
Die englisch Meldung will sagen - Du kannst jetz am Extruder arbeiten, die
Achsen sind bockiert, die Motoren sperren die Achsen weil sie unter Strom
stehen, weil sie eingeschaltet sind.

to work out that this can't be resumed.

This won’t reduce the string storage in the end, but it makes the
language files smaller. Also removed remaining unused strings.

Add 4th extruder

* Depending on extruder count, will add menu items for ultralcd to edit
individual PID parameters for each extruder
* Added menu items to each language_xx.h
* Builds OK, but recommend testing with typical LCD

This reverts commit 2b9722f387.

To test/enable, uncomment the #define DELTA_CALIBRATION_MENU in Configuration.h

Breaking up languages.h makes it easier to translate. Using language
codes makes it easier to select a language and sets the naming standard.