Revert the breaking change(s):

• getComponent/addComponent/etc. now return a pointer (sorry). This may be changed back in the future, I mainly did this so I can make a wrapper pointer class (but we'll see if it's even necessary).

BREAKING CHANGES:

• getComponent/addComponent/etc. now return a pointer (sorry). This may be changed back in the future, I mainly did this so I can make a wrapper pointer class (but we'll see if it's even necessary).
• Removed CRTP requirement for Components and Systems
• Supply list of component requirements/exclusions via variadic template (e.g. `struct MySys : System<Requires<Foo,...

Features:

• Changed how Entities are stored
• Added unit tests
• Added CMake support
• Removed virtual process/update method in System classes, as not all systems require to be updated in a particular way
• Added C++11 support where necessary, e.g. for ComponentFilter
• Library requires C++11 now - may change in the future
• Added Rendering example
• Added Animation example

Features:

• Added World::getEntities()
• Added World::clear()
• Added Movement example
• Added Collision example (thanks to johnmarinelli)

Bug Fixes

• Fixed Entity::Id's being re-cycled incorrectly.
• Fixed issue where re-activating Entities caused them to be re-added to their Systems.
• Added the ability for an empty Entity handle to check its validity...