New Icons, Various other changes

[apcro]

Add New Icons Issue #4

• Adds a new App Icon
• Adds a new Return icon

Add some simple Preferences Note: The ball must be returned to the Dock and relaunched for changes to apply

• Turn sound on and off Issue #11
• Change the ball colour (Red, Green & Blue) Issue #16
• Change the ball size (from half-size to double-size) some of Issue #20, some of Issue #16

Remove some commented-out code Update the App Menu

[!NOTE]
I realised after pushing the changes that I'd done all the work on the main branch, hence the list of changes in a single PR instead of multiples. Happy to split this into multiple PRs if desired.