Add optional target IP parameter to setup()

[IgitBuh]

Allows providing a target IP for setting up wifi credentials instead of broadcasting them.

See issue #618 for details.

[felipediel]

Hi @IgitBuh. Thanks for working on this!

Please...

1. Rename "target_ip" to "ip_address"
2. Use the constant DEFAULT_BCAST_ADDR instead of "255.255.255.255".
3. Create the PR against the dev branch.

[IgitBuh]

1. Rename "target_ip" to "ip_address"

My intention was to make it clear that in contrast to other IP parameters like in hello() this is not the local IP but the target IP. Maybe target_ip_address then? I actually don't mind either way, I just wanted to point this out.

2. Use the constant DEFAULT_BCAST_ADDR instead of "255.255.255.255".

Are you sure? It is currently used multiple times like this. If you want to change it to a constant, you should probably change all occurrences. I'm not even sure where DEFAULT_BCAST_ADDR is defined.

Would you mind doing these changes yourself to your liking? I don't have the Broadlink device with me right now and cannot test any modifications.

[felipediel]

Ok, done.