add a print_jacobian() function

[zingale]

this is useful for debugging

[zingale]

for the nova network, this outputs something like this:

*         H1        H2        He3       He4       Be7       B8        C12       C13       N13       N14       N15       O14       O15       O16       O17       F17       F18       e         
H1            1  7.12e-22 -1.07e-21  1.08e-26  6.67e-28 -7.62e-28 -3.35e-22 -4.54e-24  -1.2e-21 -1.03e-21 -1.24e-27  1.68e-21  1.11e-21 -1.16e-23 -7.92e-28  1.23e-23 -4.61e-26 -0.000775 
H2     4.34e-17       769  1.69e-19 -2.26e-19  1.52e-25  4.31e-47  1.89e-41  2.57e-43  6.78e-41  5.83e-41  7.02e-47  -9.5e-41 -6.28e-41  6.56e-43  4.47e-47 -6.97e-43   2.6e-45   -0.0013 
He3    2.89e-17       512         1 -3.77e-20  3.79e-22   3.1e-47  1.36e-41  1.85e-43  4.88e-41   4.2e-41  5.05e-47 -6.84e-41 -4.52e-41  4.72e-43  3.22e-47 -5.02e-43  1.87e-45     0.665 
He4   -1.03e-25  1.51e-06 -3.66e-24         1 -9.15e-24 -1.43e-52  7.03e-30 -8.54e-49 -1.24e-24 -7.37e-27 -2.34e-52 -1.02e-25  2.09e-46  1.53e-24 -1.49e-52  1.23e-25  9.48e-27  1.96e-09 
Be7    2.63e-19      4.25  7.19e-19  1.14e-18         1  1.73e-22  7.76e-42  1.05e-43  2.92e-41  2.39e-41  2.88e-47 -3.89e-41 -2.57e-41 -1.48e-42  1.83e-47 -4.27e-43 -9.76e-45   0.00553 
B8           -0 -2.81e-07 -4.75e-26 -6.54e-26 -4.28e-32         1  5.31e-48   7.2e-50  1.89e-47  1.64e-47  1.97e-53 -2.67e-47 -1.76e-47  2.84e-49  1.25e-53 -1.87e-49  1.35e-51 -3.65e-10 
C12    6.64e-22  -0.00124 -2.11e-22  2.81e-22  -1.9e-28 -5.92e-49         1  3.34e-45  8.63e-21  7.58e-43  9.12e-49 -1.24e-42 -8.16e-43  1.11e-29  5.81e-49 -9.09e-45  3.11e-47 -1.62e-06 
C13    1.84e-21   -0.0134 -2.28e-21  3.04e-21 -2.05e-27 -2.34e-48 -8.71e-43         1  3.13e-42  2.58e-20  3.24e-48 -4.38e-42 -2.89e-42  2.56e-44  2.06e-48 -3.25e-44  9.11e-47 -1.75e-05 
N13     3.9e-22  -0.00175 -2.97e-22  4.03e-22 -2.68e-28 -4.19e-49 -1.64e-43 -1.66e-28         1  5.04e-43  6.07e-49  5.48e-21 -5.43e-43  2.58e-23  3.87e-49 -6.08e-45  1.87e-47 -2.28e-06 
N14    1.82e-22  -0.00128 -2.18e-22   2.9e-22 -1.96e-28 -2.28e-49 -8.53e-44 -1.16e-45 -3.06e-43         1  3.17e-49 -4.29e-43  2.74e-21  2.52e-45  2.02e-49 -3.18e-45  1.21e-25 -1.67e-06 
N15    3.06e-18     -14.7 -2.49e-18 -8.94e-18 -2.24e-24 -3.35e-45 -3.68e-17 -1.77e-41 -3.22e-37 -4.02e-39         1 -6.55e-39 -4.33e-39  3.71e-21  3.08e-45 -4.69e-41  2.64e-43   -0.0191 
O14   -3.28e-26 -3.82e-08 -6.48e-27   1.4e-25 -5.83e-33  2.24e-53  1.03e-47  1.39e-49  3.66e-47  -1.4e-27  3.81e-53         1  3.79e-47 -5.69e-49 -2.43e-53  5.58e-25 -2.57e-51 -4.97e-11 
O15          -0 -1.44e-10 -2.44e-29  3.25e-29  -2.2e-35 -9.99e-57 -2.72e-51 -3.69e-53  -9.8e-51 -8.39e-51 -8.13e-28  1.37e-50         1  3.01e-48  6.44e-57 -1.04e-52  6.63e-56 -1.87e-13 
O16    1.99e-24 -1.15e-06 -1.95e-25   2.6e-25 -1.76e-31  -1.6e-51 -6.87e-46 -9.33e-48 -2.46e-45 -2.12e-45 -2.55e-51  3.46e-45  2.28e-45         1  1.63e-51  3.38e-23  9.21e-50  -1.5e-09 
O17    1.08e-20   -0.0126 -2.13e-21    -4e-20 -1.91e-27 -9.07e-48 -3.84e-42 -5.21e-44 -1.37e-41  -1.5e-19 -1.42e-47  1.93e-41 -3.97e-40 -1.94e-43         1 -1.36e-43  8.06e-22 -1.63e-05 
F17          -0 -2.41e-10 -4.08e-29  5.44e-29 -3.67e-35 -1.67e-56 -4.55e-51 -6.18e-53 -1.64e-50  -1.4e-50 -1.69e-56  2.29e-50  1.51e-50 -7.49e-53 -1.54e-27         1  1.24e-48 -3.13e-13 
F18    1.78e-20   -0.0495 -8.39e-21    -6e-20 -7.55e-27  -1.7e-47  -6.9e-42 -9.36e-44 -2.46e-41 -2.13e-41 -2.56e-47  3.47e-41 -2.67e-19 -3.31e-43 -1.63e-47  2.47e-43         1 -6.43e-05 
e      -3.4e-37         1  1.69e-19 -2.26e-19  1.52e-25  2.22e-46  1.25e-40  2.07e-42  5.93e-40  2.39e-40  3.79e-46 -7.78e-40 -2.58e-40 -1.62e-42  3.93e-46 -5.29e-42 -7.48e-45   -0.0013