* Header files moved into include/stlink
* doc/tutorial.{pdf/tex} converted to markdown for rendering by github and easy editing
* Remove `stlink-` suffix from some C source files and move into `src/tools`
* Fixup #318 serial print in stlink probe with trailing zeros
* Refactor stlink-usb.h with some doxygen-style comments
* Refactor some pieces of stlink_open_usb
* 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