Pysolid

This is a maintenance release for bug fixes only, no new features are introduced.

Contributors

+ Zhang Yunjun
+ Panji Brotoisworo

+ add `pysolid` to the `conda-forge` channel (https://anaconda.org/conda-forge/pysolid) by Joseph Kennedy.
+ simplify the installation by leveraging `pip` and `setup.py` to compile the Fortran code by Joseph Kennedy.
+ add `circleci` build and test routine.
+ standardize code structure:
- change to `src` layout
- rename `test` to `tests`

Contributors

+ Joseph Kennedy
+ Zhang Yunjun
+ Panji Brotoisworo

+ `solid.for`: update the leap second table's expiration date from 2019-Jun-30 to 2021-Dec-28 ([IERS bulletin C 61](https://hpiers.obspm.fr/eoppc/bul/bulc/bulletinc.dat))
+ `grid`: use `datetime.datetime` object for the time of interest, to replace `YYYYMMDD`, for more flexibility.
+ Improved compatibility of the C extension `solid.cpy*.so` files, by constraining the numpy version during the pre-compilation. It works in macOS and Linux with the following combination:
- Python=3.6/3.7/3.8 and NumPy>=1.18.1
- Python=3.9 and NumPy>=1.19.5
+ Improved `test.py` and `precompile*.sh`.

Contributors

+ Zhang Yunjun

+ fix the bug of input arguments checking in `solid.for` and update C extensions accordingly.
+ add `docs/plot_point/grid_SET.ipynb` with nbviewer rendering link.

Contributors

+ Zhang Yunjun

The first release of PySolid.

+ add/modify `solid.for` from Dennis Milbert for solid Earth tides (SET) calculation following the 2003 IERS Conventions by yunjunz sssangha.
+ add two modes at Python level to call Fortran code for SET calculation with API usage and examples by yunjunz:
- `point` for 1D tides time-series at a specific point for a given time period
- `grid` for 2D tides matrix at a specific time for a given spatial grid
+ add `setup.py` and pre-compiled C extensions to support `pip install git+https://github.com/insarlab/PySolid.git` by yunjunz.