Enure that autostart blocks other @RunInMain PLCObject methods, and _unblocks_ them once autostart is done...

Fixed Discovery panel in URI Editor dialog : double click works back again, and avoid setting URI to unicode type.

Bigger chunks, from 16k to 1M

Empirically reverted calls done just after NewPLC back to the order as it was before chunked transfer. Apparently I broke something... To be continued