White Screen improvement when start

Patch from repetier which seems improve LCD initalisation
Fix File Select Crash

Patch from repetier about crash when selecting file on SD Card
Remove void casting, add define, control scope

patch from repetier:
Remove void casting, add define, control scope, set string as const,
this should help to avoid bad memory management.
Merge pull request #2 from luc-github/davinci

Merge from luc-github