Add support for FX5 / Digital Enlightenment USB DMX interfaces

AFAIK there is currently no direct way to use FX5 / Digital Enlightenment USB-DMX interfaces with QLC+, not even with ola or DMX4Linux. This pull request adds a driver for these devices directly integrated as plugin for QLC+.

Contains both input and output support, using the reference fx5 driver from https://github.com/fx5/usbdmx.git (which is under the BSD license, for this I made very few modifications to it so that improvements to the reference driver in the future can directly be implemented into QLC+).

Yet only works on Linux, but it should be possible to link to Mac / Windows implementations of the HID API as available from the reference driver repo, it propably only requires copying the implementations to subfolders and editing the .pro file.
Unfortunately, I do not own Windows or Mac machines to compile it on, but I could access machines of both platforms to test builds on.

Contains German translation and udev rule, the hidapi.h and hid.c implementation for Linux are included, so that no more external dependencies are created.
Please make sure the code is ok, I have never before used anything Qt.

Tested with a Digital Enlightenment device in Archlinux.