In C api, rename event -> equeue for functions operating on queues

[geky]

Changed C api to indicates primary object these functions operate on, which is the queue.

event_call       -> equeue_call
event_call_in    -> equeue_call_in
event_call_every -> equeue_call_every
event_alloc      -> equeue_alloc
event_dealloc    -> equeue_dealloc
event_post       -> equeue_post
event_cancel     -> equeue_cancel

These were initially prefixed with event, since they associated with single events in the queue. However it became quickly apparent that this just led to confusion.

Unfortunately, the event prefix hasn't been completely removed and remains in the funtions that directly operate on events:

• event_delay
• event_period
• event_dtor

cc @kilogram