#721 Fluent substructure search mappings

[John May]

Adds a fluent API on top of the iterable permutations. Allowing much cleaner interaction -

Pattern pat = Pattern.findSubstructure(query);

for (Map<IAtom, IAtom> m : pat.matchAll(target)
                              .uniqueAtoms()
                              .toAtomMap()) {

}               

From first commit on Jan 7th: pathc/fluent-sss - forgot to reset from the hydrogen manipulator, sorry.

[Egon Willighagen]

Rebased branch at: https://github.com/egonw/cdk/compare/500-m-fluentSSS?expand=1

[Egon Willighagen]

Nice. Applied and pushed.