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 remote-tracking branch 'upstream/Marlin_v1' into Marlin_v1
Merge pull request #485 from Banjer/Panelolu2_Melzi

Add Panelolu2 support for Melzi
Merge remote-tracking branch 'upstream/Marlin_v1' into Marlin_v1
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
Merge remote-tracking branch 'upstream/Marlin_v1' into Marlin_v1
Revert and extend previous change pin check change

Reviert previous change of #if BLAH_PIN > 0 to #if defined(BLAH_PIN) &&
BLAH_PIN > -1. Unfortunately some times pin 0 is used. For my sins I've
gone through and replaced all unsafe checks of #if BLAH_PIN > -1 with
the safe version.
Merge pull request #490 from buildrob101/Marlin_v1

Revert previous change pin check change
Merge remote-tracking branch 'upstream/Marlin_v1' into Marlin_v1