effort and summary complain if you `| head` them

If you do a git-effort or git-summary and pipe it to head, the programs complain about dying and maybe trigger other errors.

[~/.oh-my-zsh on ⇄ master]
$ git effort | head -4

  file                                          commits    active days

  .gitignore................................... 19         16
/usr/local/bin/git-effort: line 165: test: : integer expression expected
error: git-effort died of signal 13
[~/.oh-my-zsh on ⇄ master]
$ git summary | head -4

 project  : oh-my-zsh
 repo age : 6 years
 active   : 1415 days
error: git-summary died of signal 13
[~/.oh-my-zsh on ⇄ master]
$

Also, it seems like it leaves the cursor invisible when that happens.

I think they should play well with head/tail/other stream filters: not emitting errors, cleaning up terminal settings, and maybe turning off the colorization when they're going to a stream and not a tty, so you can get clean plain text output if you want to.

Start by reproducing the issue with git-effort | head -4 and git-summary | head -4, then inspect the git-effort and git-summary command entry points. Confirm how SIGPIPE, terminal settings, and color output behave when stdout is not a TTY. Done means stream filters produce no spurious errors, terminal state including cursor visibility is restored, and piped output is clean.