Add Doxyfile and doxygen comments. #34

	name: tests
	on:
	push:
	pull_request:

	jobs:
	tests_on_ubuntu_x86_64:
	name: Tests on Ubuntu (x86_64 and i686)
	runs-on: ubuntu-latest
	steps:
	- uses: actions/checkout@v2
	with:
	submodules: true
	- name: Install packages
	run: \|
	sudo apt update
	sudo apt install -y gcc-multilib
	- name: run tests
	run: \|
	make check
	- name: dlopen in cloned thread
	run: \|
	cd tests && ./test-prog-x86_64 x86_64 --cloned-thread

	tests_on_mac:
	name: Tests on MacOS (x86_64)
	runs-on: macos-latest
	steps:
	- uses: actions/checkout@v2
	with:
	submodules: true
	- name: run tests
	run: \|
	sudo make check

	tests_on_windows:
	name: Tests on Windows (x64 and x86)
	runs-on: windows-latest
	steps:
	- uses: actions/checkout@v2
	with:
	submodules: true
	- uses: ilammy/msvc-dev-cmd@v1
	with:
	arch: x64
	- name: x64 -> x64 tests on Windows
	shell: cmd
	run: \|
	nmake -nologo -f Makefile.win32 check
	if %ERRORLEVEL% neq 0 exit /b %ERRORLEVEL%
	copy tests\test-prog.exe tests\test-prog-x64.exe
	nmake -nologo -f Makefile.win32 clean
	- uses: ilammy/msvc-dev-cmd@v1
	with:
	arch: x86
	- name: x86 -> x86 tests on Windows
	shell: cmd
	run: \|
	nmake -nologo -f Makefile.win32 check
	- name: x64 -> x86 tests on Windows
	shell: cmd
	run: \|
	cd tests && .\test-prog-x64.exe

	tests_on_alpine_x86_64:
	name: Tests on Alpine (x86_64 only)
	runs-on: ubuntu-latest
	container: alpine
	steps:
	- name: Install packages
	run: \|
	apk add gcc musl-dev git make
	- uses: actions/checkout@v2
	with:
	submodules: true
	- name: run tests
	run: \|
	make check

Provide feedback