I've increased various thresholds so that we can now take 3000us (3ms) waveforms.

The changes are:
* /Experiment/MAX_EVENT_SIZE in ODB is now 50,000,000
* /Experiment/Buffer sizes/SYSTEM in ODB is now 500,000,000
* max_event_size for V1725 frontend is now 45,000,000 (we use this in several places, so I now have `#define V1725_MAX_EVENT_SIZE 45000000` in v1725CONET2.hxx)
* event_buffer_size for V1725 frontend is now big enough for 10 of these largest events

The main data-taking works smoothly with 3ms traces, albeit at a low event rate. 

However protoDisplay segfaults after a few events. The backtrace is random each time, so we're clearly overflowing a buffer somewhere. I will try to look into it, but it will probably be painful and I don't think it's the highest priority issue to fix (it works "fine" for the usual 200us waveforms).