FIX: webSocketFilter when connection is lost

closeWebSock should set state to WS_STATE_CLOSED.
Provided via els: waitForReadyState examining webSock->state.
FIX: Clearing HttpTxt flags in httpSetFilename.

Missing "~" on bit and.
CLEAN: Change mprError to mprLog at level 2 for connection errors.
CLEAN: Change HttpConn.error to be a count.

Increment HttpConn.error and connError to increment for each error.
DOC: Update comments.
UPGRADE: mpr pak

Fix trace in cache.
REFACTOR: Change HttpStage open to take a return status code.

If HttpStage.open gets an error, its close() callback should not be invoked. To handle this, open must return a status code.
If the handler open() calls httpError, the passHandler needs to be used instead thereafter.
Also need more robust pendingFinalize if httpError is called before the pipeline is fully constructed.