Logging system rework

* use one central unified log with channels/priorities ad-hoc listener registration and de-registration
* disable buffering by default
* add multi-threaded ringbuffer implementation
* use buffered listener for the gui (using the ringbuffer)
rename conlog gui file and set the logbuffer-consumed flag sooner
use a more compact method to add and remove listeners t o all channels
Merge pull request #371 from Bigpet/newlogtemp

Logging system rework