BioSemi discontinuity triggers

[arnodelorme]

A single BioSemi BDF file may contain multiple recording epochs. Discontinuities are marked in bit 16 of the trigger channel (http://www.biosemi.com/faq/trigger_signals.htm). Discontinuities should be marked with a boundary event at import to avoid DC artifacts. This is particularly important for filtering.

Additionally, marking/rejecting segments with CMS out range might improve observed data quality.

We now need an exemple file with such a discontinuity.