Produces MAT file from WFDB format

[Lucas-Mc]

Introduces the conversion of WFDB files to MAT format. All data was written to the .mat file using struct.pack() so no outside packages were introduced.

This implementation conserves the -f and -t options for setting a desired start and stop time respectively, though the units here are samples instead of seconds. The -h option can be used using help(wfdb.wfdb2mat). The -H option can not be implemented here at the moment since all high-resolution content is read first through the rdrecord function which must be changed to allow this. The -l option can be used with the -f and -t options in combination. The -s option is implemented by allowing the user to select their desired channels based on the integer value of the signal number. The -S option was not implemented here due to its limited potential use.

Furthermore, I added functionality to write the .hea file as well to accompany the generation of the MAT file so that it can be read again with rdrecord and complete the cycle!

[Lucas-Mc]

Something else cool to note is that a MAT file can now be created from an EDF or WAV file since rdrecord now allows reading of those formats into WFDB format!