Enhancement while Implementing libyt in Enzo

[cindytsai]

Enhancement while Implementing libyt in Enzo

• Add new data type YT_LONGDOUBLE, which is C data type long double.
• Define PY_UFUNC_UNIQUE_SYMBOL for NumPy import. (by @matthewturk)
• yt_set_UserParameter* can now set n-vector. No longer constrain to scalar or 3-vector.
• Index offset no longer need to be 0-indexed. Previously, it should be 0-indexed.

Notes

• There will be other PR before our paper submission.

Related PR

• Enzo (https://github.com/enzo-project/enzo-dev/pull/209)

Tests

Test in both serial (mpirun -np 1) and parallel (mpirun -np 4).

• [x] example
• [x] GAMER
• [x] Enzo