Add version information

[minus7]

The --version command line switch as well as the get_version IPC command (see #98) could use this information. Should probably generated at compile time.

i3 IPC version information includes:

{
    "human_readable": "4.10.3-347-g586854b (2015-07-30, branch \"makepkg\")",
    "major": 4,
    "minor": 10,
    "patch": 3
}

[ddevault]

Yeah, we need to figure out how to make cmake read the git tags (and also start tagging versions). Blocked until I decide to mark the first version of sway.

[ddevault]

@Luminarys @minus7 IPC reminder

[minus7]

IPC taken care of, just needs to be patched up with better version information.

[ddevault]

For the sake of everyone who isn't on IRC, sway will start being versioned once wlc starts being versioned.

[Luminarys]

I'll work on improving the version information later tonight. Do you still want to do everything through macros defined at compile time?

[ddevault]

Yep.

[Luminarys]

I'm closing this for the time being, as the output is now essentially the same as i3's with the exception of the version.