Add sound

[Klevh]

Use SDL2 to add sound utilities

• Bind sound to animations (continuously and on occurrence)
• Bind sound to a window (which can optionally be blocked if window not focused)
• Add sound on event occurrence (on element AND on window)

[Klevh]

Also create a global sound management to load sounds at the beginning of the program then use them when needed with their index

[Klevh]

Add a "register sound" function to add a global sound, and return its index for future use

Add a window music played when the window has the focus

Add a sound by events for Windows and elements

Add sound binding to animation transition