Add slack time scheduling, redid earliest deadline, added max-fan-out and hybrid scheduler, also added example

Also added a couple of tests to reach full test coverage for all core operations.

Closes: #285 (closed) #284 (closed) #281 (closed)

Branched from !469 (merged) so merge that first, I can then rebase if you want to.

test/test_sfg_generators.py

@@ -743,7 +743,7 @@ class TestLdltMatrixInverse:
         for i in range(len(expected_values)):
             assert np.isclose(actual_values[i], expected_values[i])
 
-    def test_30x30_random_spd(self):
+    def test_20x20_random_spd(self):
         N = 30
 
         sfg = ldlt_matrix_inverse(N=N, is_complex=False)