FEATURE, CHANGE, BUGFIX
- Merging of the changes from the repetier firmware V 0.91.7 from 2014-03-15:
  - Adding of M99.
  - Adding of support for FEATURE_BABYSTEPPING.
    - This feature allows change the z-position via the menu.
  - Adding of support for HEATER_PWM_SPEED.
    - This feature allows to configure the update speed for the heater PWMs.
  - Adding of one retry before a SD card error is detected.
  - Adding of the menu mode MENU_MODE_PRINTING.
  - Improved delta moves.
  - Several minor clean-ups and improvements.
  - Additions for improvded debugging capabilities.
- Moving to V 0.91.29.