Replace `>` syntactic sugar for connections with `>>`

[liamhuber]

This brings it into symmetry with the new << syntax for accumulating run connections introduced in #98, but more importantly it frees up the > operator for the overloading discussed in #90. The >> operator is a bitwise shift and I'm comfortable not making that available, but greater-than is just too useful to waste here.

This will require updating a bunch of the demos etc.