Please commit/fix GAMysqlBinReader>>#timeStampFrom:

Hi,

on Pharo5 and "latest"(?) stable release of Garage it is implemented as:

timeStampFrom: aStream "ByteStream"
        | dt |
        dt := self dateTimeFrom: aStream.
        ^ dt ifNil: [nil] ifNotNil: [dt asTimeStamp]

There is no implementor of asTimeStamp. From what I read is a TimeStamp is a reduced range and asTimeStamp can be omitted?

thank you
        holger