A couple of tests were failing with the Intel compiler due to
imprecision in comparing floating point values.
Also snuck in some minor documentation fixes in a comment for
FunctionInterface.
It's easy to put accidently put something that is not a valid tag in a
ControlSignature or ExecutionSignature. Previously, when you did that
you got a weird error at the end of a very long template instantiation
chain that made it difficult to find the offending worklet.
This adds some type checks when the dispatcher is instantated to check
the signatures. It doesn't point directly to the signature or its
parameter, but it is much closer.
Instead of just checking that a dispatcher's Invoke input is an
ArrayHandle, also check that the ValueType of the ArrayHandle is
compatible with the types of the worklet operator. This is done by
adding a template argument to the ControlSignature tags that is a type
list tag that gets passed to the type check.
The Transport class is responsible for moving data from the control
environment to the execution environment. (Actually, it might be more
accurate to say it gets the execution environment associated with a
given control object.) The Transport class is templated with a tag that
controls the mechanism used for the transport.
