Porting more efficient closure(), closureStar(), and compose() functions from pdb.fast.
Moving static factory methods to DateTimeValues.
Changing visibility to protected; same visibility as previous constructor.
Moving static factory methods to SourceLocationValues.
Moving static factory methods to all pdb.fast implementations.
Unifying calls to factory method instead of calling constructor directly.
Unifying calls to factory method instead of calling constructor directly.
Unifying calls to factory method instead of calling constructor directly.
Unifying calls to factory method instead of calling constructor directly.
Unifying calls to factory method instead of calling constructor directly.
Merge branch 'master' of https://github.com/impulse-org/pdb.values