Add C support

[omdxp]

Is your feature request related to a problem? Please describe. A C library for kuliya.

Describe the solution you'd like A library under c/ folder

TODOs

• [x] #66
• [x] #67
• [x] #68
• [x] #69
• [x] #70
• [x] #72
• [x] #75
• [x] #79
• [x] #81
• [x] #89
• [x] #91
• [x] #92

Additional context

• https://github.com/zserge/jsmn
• https://conan.io
• https://docs.conan.io/2.0/tutorial/consuming_packages/build_simple_cmake_project.html
• https://cmake.org
• https://conan.io/center
• https://docs.conan.io/en/1.17/uploading_packages/bintray/conan_center_guide.html
• https://www.doxygen.nl
• https://github.com/libcheck/check
• https://github.com/cpputest/cpputest