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/embedded_files.md

@@ -0,0 +1,21 @@
+---
+layout: page
+---
+
+# Embedded Sound Files
+
+By using the open SNDFILE with a file descriptor function:
+
+    SNDFILE*  sf_open_fd (int fd, int mode, SF_INFO *sfinfo, int close_desc) ;
+
+it is possible to open sound files embedded within larger files. There are
+however a couple of caveats:
+
+* Read/Write mode (SFM_RDWR) is not supported.
+* Writing of embedded files is only supported at the end of the file.
+* Reading of embedded files is only supported at file offsets greater than zero.
+* Not all file formats are supported (currently only WAV, AIFF and AU).
+
+The test program **multi_file_test.c** in the **tests/** directory of the source
+code tarball shows how this functionality is used to read and write embedded
+files.