Remove leftover blank line
Do not test invalid arguments if no intendet exception is occuring
Add more information about the initialization of Core objects
Add #velocity attribute to the ParallaxBackground class
Add #== method to Core::LoopingScene, to help with the testing
Improve the Core::ParallaxBackground spec according to the made changes
Fix grammatical mistake in the documentation of Core::Bullet#dead?
Test Core::LoopingScene#initialize with all valid types
Add spec for Core::Bullet