Snapshot of failure tolerance changes.
Added a lot of logging to error, trace and message logs which should help the user to handle errors which can't be automatically resolved, like attempt to use nonexisting database.
Merge branch 'develop' into MAX-11

Conflicts:
	server/include/server.h
	server/modules/monitor/mysql_mon.c
	server/modules/protocol/mysql_client.c
	server/modules/routing/readwritesplit/readwritesplit.c
	utils/skygw_debug.h
Completed merge, fixed print delay to simple one.
In dcb.c:dcb_close DCB is removed either before or after the call dcb->func.close. Since mysql backend protocol sends COM_QUIT and thus, writes to backend DCB, it is kept in DCB_STATE_POLLING until the write is completed.
dcb.h: define ERRHAND temporarily since changes are still behind that macro
Defined two error handling actions in router.h: ERRACT_NEW_COMMECTION and ERRACT_REPLY_CLIENT.
Failed database is logged at expanding frequence to error and to message log due changes in mysql_mon.c. Added two new members in MONITOR_SERVERS: mon_err_count, and mon_prev_status so that each backend can be treated individually.

Error handling: if mysql_backend.c:dcb_read fails, router's handleError is called instead of closing session.
	If mysql_client.c:SESSION_ROUTE_QUERY fails router's handleError is called instead of sending error to client.

	readwritesplit.c:select_connect_backend_servers is modified so that in can be called during active router session. When called, it attempts to find one master and maximum number of configured slaves in correct state if necessary.
	When handleError needs to replace failed unit it now calls select_connect_backend_servers.
dcb.c, gw_utils.c, mysql_server_protocol.h, mysql_client.c : Replaced gw_read_gwbuff with dcb_read in mysql_client.c:gw_read_client_event.

rwsplit.sh, test_sescmd.sql : Added test case for session commands.
Fixed many error handling issues regading to timing and multiple threads.
Added flags to those backend references which have sent something to backend which causes the backend to send results or reply back. Didn't add removal of the flag since there's currently no way to tell whether response from backend contains anything else than session command reply - which aren't counted when BREF_WAITING_RESULT is set and cleared.
Added callback for rwsplit router which traverses through every rwsplit router session and for each rses, all backend references. Each bref is checked whether it is connected to non responsive server and if it is flagged to be waiting for response from the non-responsive backend. For matching ones, backend protocol's hangup function is called.
Whenever monitored server's state changes, a callback, router_handle_state_switch is called for each DCB in MaxScale session. The DCB referring to the server in question will be passed as parameter to backend DCB's hangup function.

The logic that solves the situation is not in place yet.
Modified dcb_call_foreach so that it doesn't hold spinlock (dcbspin) continuously because it caused deadlock when new slaves were tried to connect with.

Fixed a few smallish things.
When protocol closes DCB it calls dcb_close instead of dcb->func.close. dcb_close then calls dcb->func.close. This is now changed to all protocols and routers.

Rwsplit handles ERRACT_NEW_CONNECTION by clearing backend reference, removing callbacks and associating backend reference with new backend server. If it succeeds and the router session can continue, handleError returns true. Otherwise false. When ever false is returned it means that session must be closed.

Rwsplit now tolerates backend failures in a way that it searches new backends when monitor, backend, or client operation fails due to backend failure.
Some things weren't switched off from product build.
sescmd_cursor_reset didn't reset cursor's property pointer which made reset ineffective.
Merge branch 'develop' into MAX-11
Code clean up