Testing build 0.6.4 released

New updated testing build based on feedback and bug reports from the first build. This version also includes a first macOS build. 

Changes:

• To make later level progression more rewarding the board now resizes in more horizontal and vertical steps up to the max.
• The background color now changes when new vlob colors appear for more visual variation.
• Set a minimum window size to avoid some scaling issues.
• Added feedback and bug report link to the main menu.
• Added itch.io link to the main menu.

Bug fixes:

• Fixed bug with being able to place blobs outside the board if you clicked on the edge.
• Fixed Play button in main menu losing y letter when resolution is scaled down.
• Detect if fullscreen has been changed the system and update game fullscreen setting to match.
• Fixed/improved adaptive UI scaling in Settings and Credits menus.