Bugfix for filenames containing parentheses

git-list already adds quotations for filenames containing spaces. It should also use quotations for filenames containing parentheses.

Suppose you do `git-number add 3`, where `3` corresponds to `file(withParens).txt`. git-number will run:
    `git add file(withParens).txt`
Which fails. Parens ought to be escaped or placed inside quotes. This proposed fix changes git-list so that git-number instead runs:
    `git add "file(withParens).txt"`