Undocumented feature: transition easing and params

[lucemia]

• I have tried with the newest version of editly: npm i -g editly or npm i editly@latest
• I have tried ffmpeg newest stable version
• I have searched for existing issues

Transition has two undocumented parameters easing and params
Will add document after figure out the usage.

editly/index.d.ts

Lines 174 to 182 in 4b5f162

	/**
	* WARNING: Undocumented feature!
	*/
	easing?: string | null;
	/**
	* WARNING: Undocumented feature!
	*/
	params?: TransitionParams;