Experimental FiledManager implementation using shared_ptr. Turned off by default, for now.
Missing #include<string> in processcomm (reported by Feymark)
Adding 27 node quad structural element.
Adding missing virtual function to active dof.
Made PrescribedGradient b.c. use sets.
Fixing structengngmodel for when using prescribed dofs that do not belong to any nodes (internal).
Leftover cleanup changes.