Disable conversion of 'zero' and 'infinity' values in search functions when the distance type is 'python::object'

Use schedule(static, 100), to reduce overhead with small graphs in the
majority of cases.

Fully remove the filter stash and associated functions in the Graph
class, in favor of using GraphView uniquely.

This removes old dependency on an outdated graph wrapper which did edge
index housekeeping.

This returns an optional list of locations of the motifs found in the
main graph.