Add safety check to prevent exception when disconnecting while debugging

Removed DebugThread. Take advantage of the fact that buffering is done in runtime. No need to poll for traces more than ten per second, then use simple wxTimer for that. Also removed Debug Lock since now everything happens in wx' mainloop.

Rework of runtime non-real-time threading, and shared object dynamic loading :
- All exposed operations on PLCObject are now serialized through main thread
(@RunInMain). Only one exception : python trace thread calling _GetDebugData
- Re-loading of same shared object is prevented. dlclose/delte/rewrite/dlopen
don't happen in that case. This is a workaround for some xenomai copperplate
bug triggering segfault, inbetween delete and rewrite.
- Trace thread now waits for data, dies if no data, and dies instead of
suspending as before when no data consumed after 3 seconds.
- Disabled threading in Pyro client
- Enforced auxiliary threads starting sequence : Pyro -> [UI] ->
PLCWorker.RunLoop

Stripped forgotten debug code

close branch

#2476 Fix for saving text in URI edit text box. No need to click out of URI edit text box to save edited text.

Fixed Xenomai 3 PLC stop freeze. Now use explicit finish command with pipes. Closing both ends of pipes doesn't abort blocking read anymore.

More canonical test.
There is an exception happening around here in some cases when connection is dropped while waiting for answer. Not sure that this fixes it but this is anyhow better.

PLCObject got more methods serialized through worker : Start, Stop, NewPLC.
This particularly helps with initialization/startup/re-load problems
when targeting Xenomai. It should help in general for runtime robustness,
since those operations aren't meant to be executed concurrently.

Fixed implementation of runtime worker that ensure that PLCObject Load and Unload methods always run main thread.

merged

merged

Intermediate state while implementing runtime worker to ensure that PLCObject Load and Unload methods always run main thread.

Stripped more dead code.