modernize, make f2py compatible again

v1.1.1

badge

quality, robustness

Made better for use from external projects / FetchContent by:

• put tests in own directory, made optional
• added subspace::subspace CMake imported target
• implicit none (type, external)

refactor, fix c++, cleanup

add / fix meson build for c++

cleanup directory to scripts/ and src/

CI, build templates

v1.0.2`

CI OK

Modernize setup and test

• pep8, mypy, streamline into single polymorphic fortran library