Initial commit

added libraries:
opus
flac
libsndfile

updated:
libvorbis
libogg
openal

- Everything works as expected for now. Bare in mind libsndfile needed the check for whether or not it could find the xiph libraries removed in order for this to work.

Engine/lib/libsndfile/docs/development.md

@@ -0,0 +1,18 @@
+---
+layout: page
+---
+
+# libsndfile Development
+
+libsndfile is being developed by a small community of users and hackers. People
+interested in helping can raise an issue on Github.
+
+The main repository can be found on Github:
+
+<https://github.com/libsndfile/libsndfile/>
+
+and includes [instructions](https://github.com/libsndfile/libsndfile/blob/master/README.md)
+on how to build libsndfile from the Git repo.
+
+If you are interested in how to add a new format to a libsndfile, you may find
+this [FAQ](new_file_type_howto.md) helpful.