LCD: Added Deadzone at 100% Feedrate

This adds a deadzone at 100% Feedrate when changing it at the status
screen/main menu. Prevents from unwanted feedrate-changing when
navigating back to the main menu and makes it easier to return to 100%.
Add Panelolu2 support for Melzi
Merged from Upstream Master
soft tab correction
fixed merge
Merge pull request #486 from xifle/Marlin_v1

LCD: Added Deadzone at 100% Feedrate
fix broken LCD commit #dfa549f268 from buildrob - GLCD/DOGM implementation was ignored
Merge pull request #487 from MStohn/fix-bad-lcd-commit-from-buildrob

fix broken LCD commit #dfa549f268 from buildrob - GLCD/DOGM implementati...
Merge pull request #485 from Banjer/Panelolu2_Melzi

Add Panelolu2 support for Melzi
fixed typo / added "const" to defines for newer gcc compatibility
Merge pull request #488 from MStohn/fix-typo

fixed typo / added "const" to defines for newer gcc compatibility