integrate with zxing to do better intent generation on the receiver

[creswick]

Imported from trac #44.

We should put the data into an intent if we can, and zxing does this already in many cases.

Reported by: @creswick

[creswick]

We should still generate intents that the receiving application can decode it.

Support for a few common notebooks (Keep, etc) would make for a good demo, at least.

[donpdonp]

a commit is in ticket-44 that checks for plain/text and puts the data into EXTRA_TEXT which should be picked up by regular editors. I've tested it with Keep.

[creswick]

On the transmitter, I'd like to send the subject (Intent.EXTRA_SUBJECT) across the qr stream, and decode it on the far side.

I think this can be handled in MainActivity on the transmitter side, and perhaps we should provide a parameter to the ReceiveFragment so that it can decode a Job and generate an Intent (rather than specifying that logic in DecodeThread).

There is also a point in MainActivity where strings are compared with == instead of .equals(...) -- that should be changed, or it may eventually fail. (It probably works now because of string externalization, and the use of constants).

[creswick]

Mime type:

If EXTRA_SUBJECT exists:

• application/x-vnd.galois.qrstream.text-note
• data is encoded in json:
  • { 'android.intent.extra.SUBJECT': ... , 'android.intent.extra.TEXT': ...}
  • note that the JSON keys are the android intent constants.

If only EXTRA_TEXT exists:

• text/plain

We could imagine adding more custom mime types for things with CC, TO, etc.. for email formats if we wanted.

[donpdonp]

the new mime type and json encoding are implemented in the receiver and sender. ready for review.

[creswick]

Looks good - merged with master.