CI and common update:

-added webpage deploymnet stage
-added separate build stage which build all binaries and generate documentation
-added Emscripten build stage for merge to master only
-added VBO batch rendering (current default, no render mode switch yet)
-fixed camera positioning calculation
-fixed buffer issue with WebGL
-added viewport scalling (at least 300 pixels height). Pixels are scalled if screen is bigger.
-center demos gameplay area
-added fullpage html template for Emscripten build

demos/utils/source/ecs_utils/gfx/texture.d

@@ -55,6 +55,7 @@ struct Texture
             data.data[0..$] = (cast(ubyte*)surf.pixels)[0..data.data.length];
 
             glGenTextures(1, &data.gl_handle);
+            glActiveTexture(GL_TEXTURE0);
             glBindTexture(GL_TEXTURE_2D,data.gl_handle);
 
             glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);