More updates

Still working its getting there.

• Added Keymap mode switcher so using multiple keymaps is possible while in different screens, game play modes etc.
• Updated and added to the old inventory code. Adding/Removing equiping/unequiping items etc now works at least the state changes and keeping track of everything...I think. Still need to impliment some method of saving inventory and character state etc. though.
• Added some math code for general stat calculation.
• Cleaned up more of the Core module
• Moved a bit of the Core code into startup which is now launcher