Update NSIS.tmLanguage

Added new commands for NSIS 2.46 and CVS versions: FileReadUTF16LE, FileReadWord, FileWriteUTF16LE, FileWriteWord, LockWindow, Nop, RequestExecutionLevel, SectionGroup, SectionGroupEnd, SetDatablockOptimize, SetRegView, SilentUnInstall, StrCmpS, TargetMinimalOS