Allow dot "." to match newlines by default

[jakwings]

It may seems dangerous to include newlines in the output, though there is an option -0, --print0 to help.

But even if the so called "dot-all" feature is disabled, we still can match those files with empty pattern "", ^, [^/]*, etc.

[sharkdp]

I'm glad that I've never experienced a file with a newline in the name, but I think we should enable this, as you said. It's better to show these results in a potentially confusing way than to not show them at all. And -0, --print0 can help, exactly.

Note that this feature can be enabled via (?s):

> ls
'a'$'\n''b'

> fd 'a.b'

> fd '(?s)a.b'
a
b

This should be easy to implement via RegexBuilder::dot_matches_new_line.

[jakwings]

Ok, I included the patch in #96.