Spectrumwars

* Renamed "Transmitter" to "Source" and "Receiver" to "Destination" in
the public Transceiver API to reduce confusion regarding the fact
that Destination node can also send packets back to Source node. Old
class names are still supported by the game controller.
* Moved sandbox-specific code into separate modules under
spectrumwars.testbed.
* Fixed problems with some unit tests randomly failing due to race
conditions when using the mocked testbed class.
* [VESNA firmware] fixed problem with insufficient RX channel filter
bandwidth that caused packet loss on some specific pairs of nodes.
* [VESNA firmware] blink LED on packet transmission.

* Refactor payload packing out of testbed-specific code. See reference
for RADIO_CLASS attribute in Testbed class and PACKET_SIZE, binsend()
and binrecv() in Radio class.
* Documentation improvements - split documentation into Player's and
Developer's guides.
* Improved game visualizations. spectrumwars_plot now also makes a game
overview plot in addition to player specific plots.
* Record package counts separately for RX -> TX and TX -> RX.
* Various minor bug fixes.
* PyPi package.

* Add "--testbed" parameter to spectrumwars_runner for specifying the
testbed to be used.
* Add a testbed simulation class for developing player code without
access to real hardware.
* Make usrp_sensing.SpectrumSensor class usable in different testbed.
* Add documentation for developing testbed-specific classes.
* Automatically skip tests for hardware that is not currently
connected.

* Use USB CDC connection with VESNA nodes instead of serial-to-USB
converters.
* Node now waits for packet transmission to conclude before returning
from "t" commmand.
* Implement missing query methods (get_configuration,
get_frequency_range, etc.)

* Rework interface between transceiver and game controller to be
compatible with RPC.
* Add sandbox infrastructure.
* Subprocess sandboxing for player's code.

* First release