[jitsi-dev] otr4j: fix for invalid otr4j upper limit on instance tags

Hi George, all,

I've just pushed a fix I prepared a few weeks ago. (And then things got
busy and forgot to push it.) There is an unnecessarily low upper limit
to the instance tag upper limit boundary.
The otr4j specs don't specify an upper limit and the upper limit was
supposed to be the maximum possible value, but there was a mistake so
the upper limit was: 0x11111111 instead of 0xffffffff.

I've just pushed 2 commits which fix this issue. The second commits adds
some additional clarification in the code itself.

I haven't updated the otr4j library in Jitsi just yet.
Just wanted to give you a heads up.