This places all security subscriptions within a universes
Subscriptions generated via calls to AddSecurity are place in a UserDefinedUniverse
UserDefinedUniverse will serve up a predetermined list of symbols on a requested interval
LiveTradingDataFeed - reworked custom enumerators to use RefreshEnumerator as wrapper for rate limitting
Also cleans up IAlgorithm interface of unused/old methods
Slice is a new type that contains all the data from a time slice to be sent into an algorithm
Michael Handschuh