Add dtnuc_T burning timestep limiter

[maxpkatz]

PR summary

Similar to dtnuc_e and dtnuc_X, a timestep limiter dtnuc_T is added which restricts the burning from updating the temperature by more than the factor dtnuc_T * T / dT/dt.

PR motivation

For a real WD equation of state the temperature is extremely sensitive to e, so limiting the timestep based on only de/dt may allow large temperature swings. Since the reaction rates are so sensitive to T, this could mean we cannot stop large changes in T without an explicit limiter on T.

PR checklist

• test suite needs to be run on this PR
• this PR will change answers in the test suite to more than roundoff level
• all newly-added functions have docstrings as per the coding conventions
• the CHANGES file has been updated, if appropriate
• if appropriate, this change is described in the docs