Sdpa-python

Besides minor changes, this release is primarily meant to bump the version number to v7.3.0 from v0.1.0 (the pre-release in April 2023).

SDPA Multiprecision forked off from SDPA-GMP 7.1.3. The following features (from the regular SDPA 7.3.16 package) were incorporated in the April 2023 prerelease:

1. Usage of `sdpa_call.{h,cpp}` and `sdpa_solve.cpp` as the backbone of the program. This allows SDPA Multiprecision to be used as a library through `sdpa_call.h` and `libsdpa_gmp.a` static library.
2. `sdpa_exe.cpp` provides an executable frontend and replaces the earlier `sdpa_main.cpp`.
3. Allowing custom print precision of the primal and dual variables by setting `xPrint`, `XPrint` and `YPrint` in `param.sdpa` file. Please read the [documentation of GNU Multiple Precision Library](https://gmplib.org/manual/Formatted-Output-Strings) to set these properly.
4. Usage of `BlockStruct` class (defined in `sdpa_block.{h,cpp}`) to reduce redundancy of code.

The addition of the ability to be used as `libsdpa_gmp`, brings it at par with the main SDPA package by functionality (currently SDPA 7.3.17). Since semantic versioning follows `major.minor.patch` syntax (and `major.minor` components are concerned with API and functionality), the version number is being bumped to 7.3.0 to match `major.minor` of the current SDPA 7.3.17.

This is the second minor release after forking off from SDPAP. It incorporates two new features:

1. Adds support for [SDPA Multiprecision](https://github.com/sdpa-python/sdpa-multiprecision), a fork of SDPA-GMP.
2. Adds `phasevalue` to the dictionary `sdpapinfo`.
- `sdpapinfo['phasevalue']` is the status of the problem solved by `sdpap.solve` while `sdpainfo['phasevalue']` is the raw status returned by the backend (i.e. `libsdpa.a` or `libsdpa_gmp.a`).
- If `convMethod` is `LMI`, `sdpapinfo['phasevalue']` should be the reverse of `sdpainfo['phasevalue']`