Bumps version for new release

Merge pull request MIT-LCP#270 from MIT-LCP/edf_header

Adds optional EDF header reader

Updates version

Merge pull request MIT-LCP#246 from MIT-LCP/mit2wav

Produces WAV file from WFDB format

Updates requirements.txt

Updates requirements.txt to specify the development environment by using exact package versions.

Infer signal length when missing, add tff reader, allow setting remot…

…e url for downloading, add channel_names option for reading

Add datetime support for records, allow multi_to_single digital fmt i…

…n certain cases, large internal refactor, add force_channels argument to rdsamp

Fixes for comparisons, wfdb plots, and downloading databases

small module doc change

Multiple API changes to core objects and io functions. Add qrs detector

and evaluator.