Major overhaul of date time.

Removes <php 5.4 issues
Adds ability to specify both a data and time default format
Cleans up code around timestamps
Lets you set a time using another QDateTime's time portion.

Other fixes.
Additional comment fixes.
property comments
Fixing comment
Merge pull request #482 from spekary/bugfix/feature-QDateTimeOverhaul

Major overhaul of date time.