This node adds easing functions as a new function node.
Originally the patch used the `BLI_easing.h` functions.
These have been reimplemented so they are less complicated and use a [0,1] unit domain.
Additional easing functions have also been added to allow finer control.
{F12801796} {F12801799} {F12801802} {F12801803} {F12801807}