make version returned by tools/ api more sane

Incorrectly logging old sequence numbers if nack count is less than 4

ristsender segfaults on SIGINT when compiled with buildtype=release

compilation fails on old mbedtls (confirmed with mbedtls 2.4.2)

Use the message structures and protocol of EAP-SRP while using SRP-6a
for the actual key exchange.

* Many bugfixes
-- most importantly fixing clock drift issues, causing packet loss when receiving clock is running to fast and "no more buffer time is left"
--don't use non blocking send on receiver data output
* Feature Null packet deletion, automatically detected on receiver, ability to turn on on sender via CLI argument
* Minor features:
--cumulative stats in receiver
--ability to calculate RTT based of XR packets (Upipe uses those)
--calculate retry deadline based on expected arrival times
--set high priority on receiver data output threads (prevents certain issues)
--log average time spend in buffer of packets

Ugly work around to (hopefully) allow encryption to work when receiving multiplexed streams

protect calling applications from our use/abuse of the url character buffer (fixes multiplex sender bug)

Change the input thread to only sleep 5ms at a time when waiting for data. This fixes a bug where the application refuses to die with control+c

Refactor dataout_fifo_queue to be per flow and not per context. Data on it was being shared by multiple flows which resulted in a totally broken buffer.

Nonce should not be generated by generate_flowid function as it sets the LSB to 0
effectively setting the nonce to 31 bits of random data.
Also rand() was not being properly seeded.

Refactor stream-id. We are now tying it to the destination port and not the source port of the internal GRE tunnel.

Group the sender peers together into a single context but keep individual separate contexts per receiver

1) We now use one library context per sender, each with it's own RTCP channel and separate SSRC
2) We now spin a thread for each UDP socket we listen to
3) We now support rist as a form of input in addition to UDP and RTP