ibr2: Add API stability disclaimer to docs
ibr2: Fix broken string formatting in tests
Add an experimental IBR2 API

(the implementation is not actually done yet)
oob: Add some namespace constants
Add some structs for out of band data
form: Add namespace constant
form: Fix broken options
form: Factor out new field construction
form: Add unstable API warning to docs
form: Make Required show up under options in docs
Start outlining a potential data forms API
Make NS autocompletion easier in compression
Add clarification to docs and minor lint fix
jid: Remove unhelpful example text.
Add Conn type to group methods in documentation
Add missing copyright comment
jid: fix Unescape documentation
XEP-0106: Create JID Escaping text transformer

Fixes #24
Remove allocations on JID string splitting

((3413c65...)) $ go test -bench BenchmarkSplit -benchmem
BenchmarkSplit-4         5000000               253 ns/op              64 B/op          2 allocs/op

(master) $ go test -bench BenchmarkSplit -benchmem
BenchmarkSplit-4        50000000                30.5 ns/op             0 B/op          0 allocs/op

See #23
Fix broken internal tests