Pipelet:
- move Pipelet.._source and Pipelet.._query to Input..query and Input..query respectively
- move all Pipelet connection methods appropriatly to Input and Output
- Greatly simplify Encapsulate as a result of these changes
- Add 4 tests in xs_core to improve Pipelet connections testing
- test/http.js: use xs.serve()._input before ._insert_source_union()
Passport_Strategies:
- Use this._input._add_source() instead of this.__add_source()
- join_strategies(): extend( {}, ... ) to avoid side effect on common_strategy
- Update documentation