Implemented 'await connect' fully. Fixed a buffering and 'reqReg' bug.

* reqReq did not reset lastReq to reqNil, this caused problems in the
new tasyncitermacro test. (await accept stopped accepting requests after
some arbitrary amount have been accepted).
* Rewritten and moved tasyncitermacro to tests/run/ so that the tester
actually tests whether it works at runtime.
* tasynciterraw is now a copy of tasyncitermacro after macro expansion.
It will be used as a control test, useful if the macro starts generating
incorrect code.