+ Defines reporting levels and document them.
+ Add API to get the default level.
+ fix indentation.
+ fix some typos.
+ Add the beginning of a reporting test.
Fixes https://bugzilla.gnome.org/show_bug.cgi?id=735665
The process is to check for a similar report in intercept_report on
the pads of the upstream element, set that report as the master report
of the intercepted report, and return REPORTER_KEEP instead
of REPORTER_REPORT.
Currently implemented tests are:
* Settup and cleanup on monitor is done properly
* Some tests in the PadMonitor are done properly, namely:
- Buffer before segment
- Buffer outside segment
- First buffer running time is always 0
- The Demuxer flow aggregation is properly checked
https://bugzilla.gnome.org/show_bug.cgi?id=736379