#56 MetaNodes do not support paths with indexers

[Dmitry Zorin]

AbstractMetaNode.GetMetaNodeByName(string name) method implementations support names in form:

Node1.Node2.Node3

but do not support names containing index references:

Node1.Node2["index_name"].Node3

[Michael Zevin]

Indexer on DocumentNode should correctly process indexed pathes...
Something like: doc["subnode.vector[\"ind5\"].fieldA"]