Add failing test for multiple behaviour updates

`updates beh` and `value beh` should only differ in whether the (then)
initial value is included. That means that `updates beh` should only
contain the last, prevailing update from any single transaction.
Fix `updates` to coalesce updates in transaction
Merge pull request #23 from pyrtsa/fix/multiple-behavior-updates-coalesce-to-last

Fix: Simultaneous Behavior updates should coalesce to last
Remove an unnecessary Context r =>
Merge branch 'master' of github.com:kentuckyfriedtakahe/sodium