* Don't use `%zx` because it's unsupported on mingw64
* Also check that no warnings happen on travis
* Prefer `unsigned int` over `unsigned`
* Install libusb through the travis whitelist instead of manually
* Test stlink against clang and gcc through the travis "compiler" flag instead of a manual matrix
* Re-add osx
* Fix warning on gcc
* Fixup README to render HTML from Markdown
* Fixup CMakeLists.txt to have a lower working minimum version
* Add .travis.yml and .travis.sh for autobuild