Rebase branch 'dev' onto branch 'master'

**TODO:** A reminder to myself that we ought to rebase the development branch onto master as soon as it is convenient for us.

This particular branch rebase is particularly important because of the numerous bug fixes it contains; events callbacks and handling (including InputMapper subsystem), fixed building err on WindowsOS / MSVCPP and so on.

- [ ] Ensure that our third-party dependencies archives, its ```README.md```, our travis-ci dependencies URL (```.travis.yml```) and so forth are up-to-date upon rebasing branches.

- [ ] ```README.md```: Use separate build status images for the dev and master branches, now that the builds are passing -- ...well, compiling, anyhow...!