MVME162 Supported in 1.5 branch, plus additional board support

The 1.5_BETA snapshot, mentioned below, is the first available snapshot with MVME162 support, after it was recently pulled up onto the 1.5 branch. Also, NetBSD/mvme68k has been confirmed to work on the latest versions of Motorola's MVME162 boards containing the Petra ASIC. [0 comments]