On the way to public release

• revisited the facility notion which was too specific (#41)
• use only english (#55)
• definition and types where not displayed in doxygen (#42)
• rename GTestConfig.cmake into GTestExt.cmake (#46)
• performance test are trough GoogleTests(#51)
• now gogle test comes as an external CMake project (#43)
• memset issue (#40)
• use CMake build system (#37)
• replace cpp-pthread features by standard C++17 ones (#38)
• Fixed bugs #56, #57, #71, #44