rename Det to Determinant
add singular predicate
add det function for Determinant

use Determinant.doit
determinant of 2x2 blockmatrix
add only_squares utility function
determinant of matmul
determinant of transpose, inverse
determinant theano printing
pretty and latex printing for determinant

_print_Determinant = _print_Abs
determinant docstring
determinant of blockmatrix without assumptions
Merge pull request #1974 from mrocklin/determinant

Determinant