updated: don't preload all available toolkits due to unsupportable conflicts, only load when required.
tweak: removed debug messaging.
updated: add ability to unsubscribe based on likeness.
tweaked: clean up signals automatically subscribed to on thread completion and improve method names for subscribing and adding.
updated: improved accessor name for thread mangager and prepare for Qt5 inclusion.
added: extra state signals for threads.
tweaked: use new methods for thread management.
updated: bumped minor due to future deprecations.