Split DateTimePair into 4 classes:
DateTimeSequence extends DateTimePair has DatePair & TimePair.
Changed access to DatePair and TimePair methods from public to default.
Rearranged variables in DateParserTest (following method signature).
Fixed bug in getNumOf() DateTimePair (1 mixed with 0 after refactoring).
Added / Modified methods in CommandParser and DateParser to use the new
Date/TimeSequence/Pair classes.
Modified AddCommand and SearchCommand to parse using
parseDateTimesInSequence().
Merge branch 'master' of
https://github.com:443/cs2103aug2014-w11-1j/main.git

Conflicts:
	TaskManagerProject/src/uml/Command.ucls