Various fixes for #9

[ob-ivan]

Fixes #9

Various improvements made:

• Handle blocked mic case.
• Add an option to clear input when button is clicked.
• Fix a bug on android.

[Daniel-Hug]

In desktop chrome, this appears to introduce a bug. In the index.html demo, if I say something, then pause for a moment (but not long enough for it to stop listening), and then start talking again, then my latter speech will overwrite the former. This is all in a single press of the button. I believe the reason I have to wait is so that the browser will set isFinal to true.

[ob-ivan]

Chrome versions are known to differ across platforms in handling microphone operations, and I don't have enough coverage to keep eye on all of them. The proposed fix worked for those versions tested at my workplace, so I'm going to stick with it. I couldn't reproduce the problem you're talking about, @Daniel-Hug , sorry.

As a result, the fork we use at my workplace has significantly diverged from the upstream, so I give up on keeping them in sync. Closing this one as a no-go.