Snow emergencies have been declared in Boston, Cambridge, and Somerville. Here's the dirt on parking and getting around: --T alerts: This should come as no surprise, but all T lines are experiencing delays of 30 minutes or more. The MBTA website has been blinking in and out, but we did get an alert that the Silver Line Routes 742 (SL2) and 743 (SL3) are being diverted and that all buses are "omitting 88 Black......