-Added .hdr format support

-Added default environment editor setting
-Added environment created by default in new projects
-Removed default light and ambient from spatial editor, to make the editor more PBR compliant

modules/hdr/SCsub

@@ -0,0 +1,9 @@
+#!/usr/bin/env python
+
+Import('env')
+Import('env_modules')
+
+env_hdr = env_modules.Clone()
+
+# Godot's own source files
+env_hdr.add_source_files(env.modules_sources, "*.cpp")