Aiming Higher

After receiving tons of feedback several new and requested features have been implemented. There is now the ability to jump, aim/shoot at high targets and access an elevator to complete the stage. Much bugfixing and code refactoring has been done for performance and scalability. Other changes include:

- Redrawn player character sprites

- Changed "Ready" intro text to "Destroy all targets"

- Added ability to aim/shoot up

- Added item boxes that reveal ammo when shot

- Item boxes replace ammo

- Added easy intro level

- Added new elevator close/open sprite animations

- Added elevator as goal to progress to the next stage

- General bugfixes