Pypubsub

* Cleanup for Python 3.7 (mostly add support for keyword-only args, use
Python 3 inspect signature/Parameter and add tests for

* Verified support Python 3.5 and 3.6
* Distribution via wheel
* Abandon support for Python 2.x and easy_install; now requires Python >= 3.3
* Abandon support for long-ago deprecated arg1 messaging protocol
* Added currying of subscribed listener args
* Significant speed improvement for message delivery
* Use PEP 484 style of annotations throughout
* Use enum instead of constants when practical

* cleanup low-level API: exception classes, moved some out of pub module that did not
belong there (clutter), move couple modules; specifically:

* Removed from pub (available on object returned from pub.getDefaultTopicMgr())
* getOrCreateTopic -> pub.getDefaultTopicMgr().getOrCreateTopic
* getTopic -> pub.getDefaultTopicMgr().getTopic
* newTopic -> pub.getDefaultTopicMgr().newTopic
* delTopic -> pub.getDefaultTopicMgr().delTopic
* getAssociatedTopics -> pub.getDefaultTopicMgr().getTopics
* getDefaultTopicTreeRoot -> pub.getDefaultTopicMgr().getRootAllTopics
* Removed from pub (available from pubsub.core):
* ITopicDefnProvider
* Moved from pub into to pubsub.core.TopicDefnProvider class as classmethod:
* registerTopicDefnProviderType
* Renamed:
* TopicNameInvalid -> TopicNameError
* UndefinedTopic(RuntimeError) -> TopicNameError(ValueError)
* UndefinedSubtopic(RuntimeError) -> TopicNameError(ValueError)
* ListenerInadequate(TypeError) -> ListenerMismatchError(ValueError)
* UnrecognizedImportFormat -> UnrecognizedSourceFormatError
* ListenerSpecInvalid -> MessageDataSpecError
* SenderMissingReqdArgs -> SenderMissingReqdMsgDataError
* SenderUnknownOptArgs -> SenderUnknownMsgDataError
* ListenerNotValidatable -> TopicDefnErrorcd
* Changed;
* Topic.isSendable -> hasMDS
* TopicManager.??? -> isTopicInUse + hasTopicDefinition

* completed the ref docs
* support installation via pip
* cleanup versioning metadata: use pubsub.__version__ instead of pub.PUBSUB_VERSION
* support Python 3
* add getListenersIter() to iterate over listeners without temp copy of listener list
* add deprecation message when import setuparg1
* new wxPubsubMonitor utility class

- cleanup of docs
- merged importTopicTree to addTopicDefnProvider
- renamed pub.getDefaultRootAllTopics to pub.getDefaultTopicTreeRoot
- removed pub.importTopicTree, use pub.addTopicDefnProvider(source, format)
- renamed pub.exportTopicTree to pub.exportTopicTreeSpec
- several minor bug fixes
- incorporated some patches contributed by users: one for performance improvement when
high-frequency of subscribers/messages; one for reading topic tree specification from
XML rather than .py module
- v1 and v2 APIs no longer supported

- added some docs
- more configurable importTopicTree
- using importTopicTree now allows to use the topic hierarchy as topic names instead of
string, thereby enabling python editors to support PyPubSub-based development via
code completion and sendMessage keyword arguments.

- cleanup docs
- couple minor tweaks (for instance added pub.getMsgProtocol())