The bezier curves functions can be expressed with string containing bezier()
function or with mojs.easing.bezier
constructor that returns a function:
// ...
easing: 'bezier()',
// or
easing: mojs.easing.path('M0,100 C50,100 50,67.578125 50,50 C50,32.421875 50,0 100,0')
// ...