Implement some GPU features (#209)

* Implement stencil testing

* Implement depth testing

* Implement face culling

* Implement front face

* Comparison functions now take OGL enums too

* Fix front facing when flipping was used

* Add depth and stencil clear values

Ryujinx.HLE/Gpu/Engines/NvGpuEngine3dReg.cs

@@ -14,6 +14,11 @@ namespace Ryujinx.HLE.Gpu.Engines
         ViewportTranslateZ   = 0x285,
         VertexArrayFirst     = 0x35d,
         VertexArrayCount     = 0x35e,
+        ClearDepth           = 0x364,
+        ClearStencil         = 0x368,
+        StencilBackFuncRef   = 0x3d5,
+        StencilBackMask      = 0x3d6,
+        StencilBackFuncMask  = 0x3d7,
         VertexAttribNFormat  = 0x458,
         DepthTestEnable      = 0x4b3,
         IBlendEnable         = 0x4b9,
@@ -27,9 +32,22 @@ namespace Ryujinx.HLE.Gpu.Engines
         BlendFuncDstAlpha    = 0x4d6,
         BlendEnableMaster    = 0x4d7,
         IBlendNEnable        = 0x4d8,
+        StencilEnable        = 0x4e0,
+        StencilFrontOpFail   = 0x4e1,
+        StencilFrontOpZFail  = 0x4e2,
+        StencilFrontOpZPass  = 0x4e3,
+        StencilFrontFuncFunc = 0x4e4,
+        StencilFrontFuncRef  = 0x4e5,
+        StencilFrontFuncMask = 0x4e6,
+        StencilFrontMask     = 0x4e7,
         VertexArrayElemBase  = 0x50d,
         TexHeaderPoolOffset  = 0x55d,
         TexSamplerPoolOffset = 0x557,
+        StencilTwoSideEnable = 0x565,
+        StencilBackOpFail    = 0x566,
+        StencilBackOpZFail   = 0x567,
+        StencilBackOpZPass   = 0x568,
+        StencilBackFuncFunc  = 0x569,
         ShaderAddress        = 0x582,
         VertexBeginGl        = 0x586,
         IndexArrayAddress    = 0x5f2,