Many quality of life fixes and updates that makes the game more playable.

• Level transitions added, settable in menu
• Updated friction for less slippery platforming
• Removed unused menus
• Fixed bug with fountains not emitting particles properly
• Added checkpoints
• Revamped saving/loading to update menu items to reflect changes (known bug: some situations still aren’t updating as expected)
• Double jump now works after using a bounce pad
• Updated spawner sprite
• Edit mode now displays the selected block name