throttling modes

Throttle decorator parameters:
 f        - function
 interval - number             - the minimum duration in miliseconds between calls
 keep     - FIRST/LAST/ALL     - which function calls will be kept if throttling must occur
 wait     - NONE/INTERVAL/IDLE - how long to wait after getting the first call before making a call
     - if NONE the call will be made immediately
     - if INTERVAL the call will be made after interval ms have elapsed since the first call
     - if IDLE the call will be made after interval ms have elasped without a call
wait-interval - optional number - can be used to override the wait interval, instead of using the standard interval.
     must be <= interval
result - OWN/ANY - what the promise result can correspond to
     - if OWN, the promise will be resolved when the input call is excecuted, else rejected.
     - if ANY, the promise will be resolved with the input call, or the call which was excuted to block the input call
 
Returns:
 a promise that will be either resolved or rejected.
 I guess we need an option for how these work 


There are different potential throttling modes.

Given a throttle interval of |----| and these input calls:

    A  B        C        D E  F

The modes will produce the following output calls:

1:  A----       C----    D----F----
(drop: ignore calls within interval of latest not ignored)
(this is the only one that can result in latest value being dropped)
( keep: first / delay: none )

2:  --------B   ----C    ----D---F
(debounce: waiting for interval of inactivity, then sending latest)
(keep: last / delay: until-inactive)

3:  A----B----   C----    D----E----F----
(throttle: make all calls, but buffer to throttle to interval)
(keep: all / delay: none )

4:  ----B       ----C    ----E----F
(lazy: after first call, wait interval than make latest call and reset)
(keep: last, delay: one-interval)

5:  A----B----  C----    D----F----
(smart: send first immediately, then after interval send latest if any)
(keep: last / delay: none )