EEG bdf reader

This code reads EEG data from a 'bdf' file

This code reads EEG data of specified length from a specified 'bdf' file. It is easier to use than traditional bdf readers and does not output some unnecessary (from author's point of view) information, such as sampling frequency for EACH EEG channel. All EEG channels are assumed as sampled at the same frequency, pre-filtered by same filters and so on...