Extended Preheat options

Preheat LCD menus base on code by D-Base
Corrections for preheat extension in language.h
semantic changes in language.h
Bugfixes for language option 6 (russian)
Merge pull request #846 from Dim3nsioneer/Marlin_v1

Extended Preheat options
Merge branch 'Marlin_v1' into mendel90_lcd
Merge branch 'mendel90_lcd' of github.com:mattsch/Marlin into mendel90_lcd