Changed semantics of pulse()

[jweisz]

Scope of Changes

• changed pulse() behavior to match that of pulseOnce() -- issuing a single pulse to the LED
• removed pulseOnce(), isPulsing(), and stopPulsing()

Rationale -- pulsing has been a very unreliable operation in Node.js (at least the way it was implemented). When pulsing continuously, the event loop of Node.js is blocked during the LED pulse. That meant the only time available for processing other things, such as the callback used in tj.listen(), was between pulses. This made for a bad user experience; the intent of pulse() was to show feedback that TJBot was listening, but by the nature of it's implementation, it wasn't able to listen during the pulse(), causing spoken input to be ignored. Removing the stateful pulse() and changing it to a single issuance of a pulse (i.e. what pulseOnce() did), makes it a bit safer to use this method in conjunction with other methods that have callbacks.

Note: accepting this PR will cause a breakage in recipes that rely on the existing API (at least where pulsing is concerned). I recommend we bump TJBotLib to v1.3 to indicate the lack of backwards compatibility with the v1.2.x series.

[victordibia]

ok.
I agree we should bump up version before any further changes.