Update piemod keymap (#2786)

Update piemod keymap (#2786)

Add RGB control, fix keymap to work with latest QMK.

Squashed commit of the following:

commit 3c5d95e4809d446fe5304aab9274d527182835e6
Author: dwrz <dwrz@dwrz.net>
Date:   Sat Apr 21 18:26:58 2018 +0000

    Make rules.mk for Let's Split piemod

commit 0cc5fc135220f0eb48509d2b027e4cad033d74a5
Author: dwrz <dwrz@dwrz.net>
Date:   Sat Apr 21 18:26:25 2018 +0000

    Add RGB control keys to function layer

commit d1b6bfa5f34123658534f99c97471b779b971ffb
Author: dwrz <dwrz@dwrz.net>
Date:   Sat Apr 21 18:26:03 2018 +0000

    Refactor MACROS to COMBOS

    MACROS was conflicting with existing code.

commit ce2f47b13fb3bfab9d63292ddba466879d300051
Author: dwrz <dwrz@dwrz.net>
Date:   Sat Apr 21 18:25:26 2018 +0000

    Add typing options to config.h

commit cb0aa62b81a17aaaee1f9843138495b9ca14b6d4
Author: dwrz <dwrz@dwrz.net>
Date:   Sat Apr 21 18:25:10 2018 +0000

    Add RGB options to config.h