-Added EXR supprot for HDR (no BC6 compression yet though)

-Improvements to texture importer
-Proper detection of S3TC compression modes, and added all modes to Image
-Fixes to non-power of 2 compressed textures, which should all be supported by GLES3

modules/tinyexr/SCsub

@@ -0,0 +1,20 @@
+#!/usr/bin/env python
+
+Import('env')
+Import('env_modules')
+
+env_tinyexr = env_modules.Clone()
+
+# Thirdparty source files
+# Not unbundled for now as they are not commonly available as shared library
+thirdparty_dir = "#thirdparty/tinyexr/"
+thirdparty_sources = [
+    "tinyexr.cc",
+]
+thirdparty_sources = [thirdparty_dir + file for file in thirdparty_sources]
+
+env_tinyexr.add_source_files(env.modules_sources, thirdparty_sources)
+env_tinyexr.Append(CPPPATH=[thirdparty_dir])
+
+# Godot's own source files
+env_tinyexr.add_source_files(env.modules_sources, "*.cpp")