added dlscript module

This module was written by bojidar-bg and me, with the help of ClikCode and touilleMan.

This adds a module to Godot that enables the use of dynamic libraries as a source for scripts.
That also allows third party libraries to be linked to Godot more easily and without creating modules.

For a readme see https://github.com/GodotNativeTools/godot_headers/blob/master/README.md

modules/dlscript/SCsub

@@ -0,0 +1,14 @@
+#!/usr/bin/env python
+
+Import('env')
+
+env.add_source_files(env.modules_sources, "*.cpp")
+env.add_source_files(env.modules_sources, "godot/*.cpp")
+
+env.Append(CPPFLAGS=['-DGDAPI_BUILT_IN'])
+
+if "platform" in env and env["platform"] == "x11": # there has to be a better solution?
+    env.Append(LINKFLAGS=["-rdynamic"])
+env.use_ptrcall = True
+
+Export('env')