Renamed the concept of 'LogFile' into 'HSTable'.

The LogFile becomes Hashed String Table (HSTable). The following
names and concepts were renamed:

LogFile => HSTable
LogfileManager => HSTableManager
LogIndex => OffsetArray
logindex => offarray
LogType => RegularType
LogFileHeader => HSTableHeader
LogFileFooter => HSTableFooter
LOGFILE => HSTABLE