Upgrade to Unity 2019.4.1f1

[Josh-McMillan]

• Upgrades project to Unity 2019.4.1f1
• Updates the .gitignore for modern Unity projects
• Resolves Issue polygon cutout is bugged in unity 2017.3.1f1 #6
• Minor fixes for Unity render API

[Josh-McMillan]

Found the fix here.
The fix was to go into each shader and modify the code from:

//Cut out polygons
if (distance > unity_FogStart.z + unity_FogColor.a * 255)
{
    o.pos.w = 0;
}

to

//Cut out polygons
if (distance > unity_FogEnd.z + unity_FogColor.a * 255)
{
    o.pos = 0;
}

Small note: I decided to change from getting the FogStart to the FogEnd, so that there were no clipped edges showing in meshes during runtime. It should now prevent the shader from clipping before the fog is set in. Not sure if this is entirely accurate, and can totally be discussed.