v0.70.0 Generic and Type Checking improvements

This release cleans up some of the semantics and workarounds required

• removes the need for buffer functions by allowing initializers on flow inputs and other fixes
• removes the buffer function from flowstdlib
• improvements to generic types for inputs and outputs, clarifying "object" is different
• data type checking on connections not just within a flow but end-to-end as connections are collapsed
• correct execution of sub-flows using same semantics as functions, holding off inputs until they complete
• removal of unnecessary blocking of sending functions within a flow, allowing more parallelism

A couple of issues remain related to flow initializers, and feedback of inputs to a flow as part of outputs (like can be done with a function) but the majority of the semantics and type checking is now working as intended.