Add Q3lite to Retropie

[hissingshark]

Been tinkering with this over the past year or so. It adds Q3lite for the RPi and Vero4k - essentially Quake 3 Arena.

It is a fork of ioquake3. It provides an updated id Tech 3 game engine running on GLES and, most importantly for this platform, SDL2.

Users are required to supply the pak0.pk3 file and license key from an original Quake 3 disc or digital download. They must install freely available game data, but cannot proceed without agreeing to its EULA.

Notes:

1. The code features several long dialog sections. These have been treated as per the CONTRIBUTING.md guidance for long pipes. Code is divided into multiple lines, with a 2 space indent after the first line.
2. Additional functions have been added. Of these the game data function in particular has analogs in other ports scriptmodules. The naming conventions differ, but in this module they adher to CONTRIBUTING.md.
3. As a new port it may require additions to the Retropie Wiki page for Quake 3. If acceptable should I directly edit that or submit an accompanying PR?

Many thanks in advance,