2014-01-24-21.36.04: src/lib/core/init/built-in.pkg:  Add rw_matrix_of_eight_byte_floats, rw_matrix_of_one_byte_unts.   src/lib/core/init/pervasive.pkg:  Add it::rw_matrix_of_eight_byte_floats::get, it::rw_matrix_of_one_byte_unts::get to (_[]) and it::rw_matrix_of_eight_byte_floats::set, it::rw_matrix_of_one_byte_unts::set to (_[]:=).  src/lib/src/overloaded-vector-and-matrix-ops-unit-test.pkg:  Switch to using overloaded (_[]) and (_[]:=) in exercise_rw_matrix_of_eight_byte_floats() and exercise_rw_matrix_of_one_byte_unts().