dalb8's review indicated that the description should be closer to what
is available on Google Play. I've included the list of supported
protocols and dropped that fact the Free Software is a good thing.
He also recommended killing the debuggable=true line, which was done
through a sed prebuild command.
The default target of android-9 was available on my machine, but not
the f-droid build server, so use the suggested alternative target of
android-10.
Otr4j is distributed as source in a separate repo but was included
in binary form in this one. For now, clone and build otr4j but in
the future an f-droid srclib will be used.