[Feature Request] Ultimaker 3 support

I have an Ultimaker 3 & Ultimaker 3 Extended at work, and we're currently using Cura to slice + send the file. I'm trying to use Slic3r, but it's kinda difficult, and some modifications are needed for a perfect compatibility.

What's needed : (probably not exhaustive for now)

• Default profile with dimensions and some default parameters
• Ultimakers are waiting for a header at the very top of the GCode. They documented it on their forum, i'll paste here with descriptions. It can't be put in "before start custom gcode" as Slic3r adds its own header… That's actually the main issue here.
• Ability to put in the header relevant infos such as dimensions, duration, volume needed.
• (actually a feature request) "wipe tower"/"purge extruder" at start : the Ultimaker extrudes like 3cm of filament in a tower before starting the print, kind of like the skirt. It can be added in the custom GCode, but a check box for this would be great.
• Printer Host upload along with Duet + Octoprint. The Ultimaker API looks kinda documented.

I don't really know the source code of Slic3r, but I'm ready to get my hands dirty if i'm not alone on this ;)