Prim's algorithm for finding MST added;
Interface accommodating MST finder facilities abstracted;
Testing facilities updated to reflect committed changes;
New test for correct MSF building added;
Revamped deprecated interface to maintain backward compatibility;
Slightly refurbished MST tests; added backward-compatibility testing facility;
Other minor updates;
MST test suite renamed;
Merge pull request #24 from alexeykudinkin/master

Prim's algorithm for finding MST added