WaitForsAPI update

I added functionality for gesture and its blocks gesture & cancel gesture:

function gesture(name : string) : void

Aside from that, I added methods for existing blocks, and changed block names as follows:

function setMessage(message: string): void && display_message => set_message
function say(message: string): void && speak => say
function gesture(name: string): void

Finally, I changed the parameter name of sleep(sec) to sleep(duration)

In my next pull request, I will add blocks for startFollowingFace and stopFollowingFace, as well as the enums.