Support option bundling

[chocolateboy]

💡 short option bundling is a massive usability enabler

I keep expecting "stuck" options to work e.g.:

$ seq 1 10 | gargs -n10 "echo [{}]"

Instead one has to write:

$ seq 1 10 | gargs -n 10 "echo [{}]"

Likewise, bundled options don't work i.e. instead of:

seq 1 10 | gargs -vd "echo [{}]"

one must write:

seq 1 10 | gargs -v -d "echo [{}]"

These short-option shortcuts are standard for CLI tools (on Unix at least) and in my experience most core/stdlib option parsers support them by default.