* ci: support coveralls
* cmake: add code coverage support
* test: run flake8 static analysis via CMake
* test: fix E741 errors by pycodestyle
* test: fix E722 errors by pycodestyle
* test: fix E711 errors by pycodestyle
* test: fix E502 errors by pycodestyle
* test: fix E501 errors by pycodestyle
* test: fix E305 errors by pycodestyle
* test: fix E303 errors by pycodestyle
* test: fix E302 errors by pycodestyle
* test: fix E301 errors by pycodestyle
* test: fix E275 errors by pycodestyle
* test: fix E251 errors by pycodestyle
* test: fix E231 errors by pycodestyle
* test: fix E203 errors by pycodestyle
* test: fix E201 and E202 errors by pycodestyle
* test: suppress E131 errors by pycodestyle
* test: fix E128 errors by pycodestyle
* test: fix E122 errors by pycodestyle
* gdb: fix Python <assert> statement usage

NO_DOC=LuaJIT submodule bump
NO_TEST=LuaJIT submodule bump
NO_CHANGELOG=LuaJIT submodule bump