Add path search with chain syntax

[bgajdero]

Add search notation by chaining properties to path search in graph.
For example, find all output hypothesis starting with Ks where:
Ks with ks_inputs in [3,4], then for all ksars have ks_status.

Example code:
Ks.search().ks_inputs([3,4]).ks_status(1).output_hypotheses

Ks.search().ks_inputs.ks_status.output_hypotheses

Using existing functions for path search, adopt dot notation for chaining values:
Node._path_search(preds={hasKsInputs, hasKsStatus, hasOutputHypotheses})