Respond to tilt --version as well as tilt version

[rmunn]

Describe the Feature You Want

The --version flag is standard among most command-line tools for Linux (e.g., https://www.gnu.org/prep/standards/standards.html#g_t_002d_002dversion among others), just as much as the --help flag. It would be nice if Tilt followed that standard as well, by having tilt --version produce the same response as tilt version.

Current Behavior

tilt --version produces Error: unknown flag: --version and then prints the usage info.

Why Do You Want This?

Most experienced Linux developers will have --version as nearly instinctive muscle memory.

Additional context
None.

[nicks]

sure, that seems reasonable