With evtclib being on crates.io now (and generally, being available
publicly through git), there is no longer a need to have a copy of the
evtclib repository in this repository. The main reason was that evtclib
was private when I started it, so the easiest way to include it was
through a git submodule. That reason is no longer valid.

If we really *need* to use the git version, it is also better to just
point Cargo to the repository and let it deal with keeping the
repository up-to-date, rather than using git submodules.

This commit also updates Cargo.lock, so there is a bit of noise from
also adding ctrlc as a dependency.