Improvements to Stream, Tuples, New Entry types, etc

Added:

• EntryString.MapToEntryBytes

• EntryByte

• Entry comparison utility function EntriesEqual

• Tuple3

• Corrections to Collector.GroupingBy finisher

Added to Collector:

• Reducing
• FlatMapping

Added to Stream:

• Limit
• Distinct
• Peek
• ForEachC (concurrent version of ForEach)

Added to Maybe:

• IsEmpty
• Get
• GetOrElse
• OrElse
• Filter

Some refactoring.