geodynamics/pylith_installer: Installer version 0 for PyLith v3.0.3

This utility is used to build PyLith v3.0.3 and its dependencies from source code on UN*X operating systems. The installer will download all necessary files for the dependencies and the PyLith code; there is no need to download any of the tarballs other than the installer distribution. See the installation instructions for more information. Install PyLith to Python virtual environment and use pip to install Python modules (setuptools, certifi, numpy, cftime). Migrate documentation to Sphinx+MyST Separate build directory for external dependencies and CIG-related code (pythia, spatialdata, PETSc, PyLith) Update versions of dependencies. gcc 10.3.0 mpc 1.2.1 gmp 6.2.1 mpfr 4.1.0 mpich 3.4.2 openmpi 4.1.1 openssl 1.1.1l libffi 3.4.2 curl 7.83.1 cmake 3.21.3 python 3.10.6 pcre 8.40 swig 4.0.2 cppunit 1.15.1 sqlite 3.31 tiff 4.3.0 proj 8.1.1 hdf5 1.12.1 h5py 3.6.0 netcdf 4.8.1 netCDF4 1.5.7 pythia 1.0.0 spatialdata 3.0.0 Remove installing dependencies that are now obsolete. ScientificPython FIAT Cython Use projsync to install PROJ datum files. Allow specification of MPICH options in configure. Provide --enable-developer configure argument to install pacakges for development