Updates usrsctp to latest code c53d43ee76673ee281806497eb43750c239c145f. Updates build instructions with new repository and some notes.

Tears down the DTLS (media) session if the fingerprint does not match the hashed certificate (i.e. conforms with RFC 5763). Generally, the Jitsi desktop client visually depicts the secure status and may want to set the ConfigurationService and/or System property org.jitsi.impl.neomedia.transform.dtls.DtlsControlImpl.verifyAndValidateCertificate to false in order to prevent the teardown.

This reverts commit ff1eb103.

This should now work as expected.

broken SRTP authentication tags when a non-zero offset is introduced
(for example from an external packet transformer). Closes #43.

Loads JNI libraries using JNIUtils instead of System in order to support binaries packed into the JAR as well.

Deletes the files which implement Speex with pure Java because we are not using them anyway and we do not want the obsolete dependency on jspeex.

addRTPExtension() is called before a StreamConnector has been set, and a
NPE when an ssrc-audio-level extension is set while there is no device
session.

java.lang.NullPointerException at
org.jitsi.impl.neomedia.transform.srtp.SRTPTransformer.transform(SRTPTransformer.java:205) at
org.jitsi.impl.neomedia.transform.dtls.DtlsPacketTransformer.transform(DtlsPacketTransformer.java:1227) at
org.jitsi.impl.neomedia.transform.SinglePacketTransformer.transform(SinglePacketTransformer.java:84) at
org.jitsi.impl.neomedia.transform.TransformEngineChain$PacketTransformerChain.transform(TransformEngineChain.java:293) at
org.jitsi.impl.neomedia.transform.TransformUDPOutputStream.createRawPacket(TransformUDPOutputStream.java:67) at
org.jitsi.impl.neomedia.RTPConnectorOutputStream.write(RTPConnectorOutputStream.java:423) at
org.jitsi.impl.neomedia.rtp.translator.OutputDataStreamImpl.doWrite(OutputDataStreamImpl.java:201) at
org.jitsi.impl.neomedia.rtp.translator.OutputDataStreamImpl.run(OutputDataStreamImpl.java:344) at
java.lang.Thread.run(Thread.java:745)

Updates the JNA library to version 4.1.0 because it is dual-licensed under LGPL 2.1 and Apache License 2.0.

Moves the FFmpeg and G722 JNI libraries from libjitsi to jitsi-lgpl-dependencies because they statically link to LGPL objects.

Ubuntu uses the linker option "--as-needed" by default. This requires that libraries are added in the correct order to the linker command line (i.e. after the objects requesting external symbols).