Improve shadow filters (#12195)

* Rewrite shadow filtering for the new distortion
* Calculate penumbra radius using a single sample
* Avoid peter-panning effect due to filtering of short shadows
* Add adaptive filter quality for soft shadows
* Avoid sharp shadows on surfaces without normals (e.g. plants)
* Increase default and maximum soft shadow radius
* Make line numbers in shader errors match the code

src/client/shadows/dynamicshadowsrender.cpp

@@ -670,6 +670,7 @@ std::string ShadowRenderer::readShaderFile(const std::string &path)
 	std::string prefix;
 	if (m_shadow_map_colored)
 		prefix.append("#define COLORED_SHADOWS 1\n");
+	prefix.append("#line 0\n");
 
 	std::string content;
 	fs::ReadFile(path, content);