ashley-1.2.0

• API addition: people requested to put Entity#getComponent(Class) back in, so we accepted SgtCODFish's PR. ComponentMapper is still the most efficient and encouraged method to retrieve an entity's components. Issue #51.
• API addition: added PooledEngine#clearPools() to delete unused entity and component pool memory. Commit 2837299.
• API addition: adds EntitySystem#setProcessing(boolean) so as to be able to enable/disable systems at will. Commit 188239a.
• API addition: adds Engine#getSystems(). Commit 8f54a2a.
• API addition: you can now listen to entity events on a per family basis. Commit f90d129.
• Crash fix: things would blow up if you deleted entities from IteratingSystem#processEntity(). Commit d5ace4e.
• Bug fix: removing listeners while dispatching a Signal would make other listeners miss the event. Thanks to vlaaad for the PR! Issue #52.
• Bug fix: some entities were skipped if the user removed an entity from the engine mid system update. Removing an entity from a system by changing its components mid iteration also caused problems, which are now solved. Issue #44.
• Bug fix: there was a problem with family membership not being properly updated when removing a component from an entity was supposed to result in said entity being added to the family. This only affected families that exclude components. Issue #56.
• Internals: small performance improvement. Issue #59.
• Others: added benchmark suite to compare Ashley's performance with Atermis'. Commit d6fec98.