New rtc dump analyzing tool in Python

tools/py_event_log_analyzer/README

+This file describes how to set up and use the RTP log analyzer.
+
+Run the tool as follows:
+
+    python rtp_analyzer.py <rtc event log>
+
+where <rtc event log> is a protobuf dump of the RTC event stream. Such

[ivoc, 2016/05/24 11:50:17]

I recommend rephrasing this a bit, for example: where <rtc event log> is a
recorded RTC event log, which is stored in protobuf format.

[aleloi, 2016/05/24 15:54:39]

Done.

+dumps are generated by Chrome through chrome://webrtc-internals

[ivoc, 2016/05/24 11:50:17]

I would rephrase to make it more clear that there are multiple ways to generate
the RTC event logs (depending on which app/program you're using). For example:
Such dumps can be generated in multiple ways, for example by Chrome through the
chrome://webrtc-internals page.

[aleloi, 2016/05/24 15:54:39]

Done.

+
+The script has been tested to work in python versions 3.4.1 and 2.7.6,
+but should work in all python versions for which there is a version
+of the dependencies.
+
+Dependencies
+------------
+
+The analyzer script needs *numpy* (http://www.numpy.org/) and
+*matplotlib* (http://matplotlib.org/). These libraries can probably be

[ivoc, 2016/05/24 11:50:17]

I don't think it's safe to assume all of our users use linux, so I think these
lines can be removed (These libraries...Debian-based systems). 

[aleloi, 2016/05/24 15:54:39]

Done.

+installed with your systems package manager, e.g.
+
+   sudo apt-get install python-numpy python-matplotlib
+
+in Debian-based systems
+
+If you use python 2, you also need *enum34*

[ivoc, 2016/05/24 11:50:17]

This might be a small/personal thing, but I prefer not to use "you" when it's
not really necessary. You could rephrase this as: When using python 2, the
package *enum34* and *future* are also needed.

[aleloi, 2016/05/24 15:54:39]

Done.

+(https://pypi.python.org/pypi/enum34) and *future*
+(https://pypi.python.org/pypi/future). These packages can be installed
+through pip, (https://docs.python.org/2.7/installing/).
+
+You also need a version of Protocol Buffers. One is distributed along

[ivoc, 2016/05/24 11:50:17]

Same here, I would recommend: A version of the Protocol Buffer library is needed
as well.

[aleloi, 2016/05/24 15:54:39]

Done.

+with WebRTC in `thirdparty/protobuf/python`. This tool also needs a
+file `rtc_event_log_pb2.py` which is automatically generated from
+`webrtc/call/rtc_event_log.proto` and placed in
+`out/<TARGET>/pyproto/webrtc/call/` with every WebRTC compilation. To
+use it, you have to compile WebRTC before using this tool.

[ivoc, 2016/05/24 11:50:17]

To generate it, WebRTC should be compiled before using this tool.

[aleloi, 2016/05/24 15:54:39]

Done.

+
+An alternative to compiling WebRTC is to install your own version of
+Protocol Buffers and the `protoc`, the Protocol Buffer compiler. On

[ivoc, 2016/05/24 11:50:17]

"the" should be removed here, so: ...Buffers and 'protoc', the... 

[aleloi, 2016/05/24 15:54:39]

Done.

+Debian-based systems, it is

[ivoc, 2016/05/24 11:50:17]

Again, too linux/debian specific. Would remove: On
Debian-based...python-protobuf

[aleloi, 2016/05/24 15:54:39]

Done.

+
+   sudo apt-get install protobuf-compiler python-protobuf
+
+If you use your own version of protobuf, generate the python file in
+this folder with
+
+   protoc -I $WEBRTC_ROOT/webrtc/call $WEBRTC_ROOT/webrtc/call/rtc_event_log.proto --python-out ./
+