- cmake: git_timestamp() returns last commit time formatted as
`YYYYMMddHHmm`.
- Always include commit hash in :version and --version output.
`nvim --version` sample output:
NVIM 0.0.0-alpha+201410070245 (compiled Oct 7 2014 05:30:45)
Commit: f747b2b1ff7bfe7eb00cc2be82d7af87c98f1111