Indexing by channel and leak channel support.

What's Changed

• Support leak channels by @easy-electrophysiology in #29
• Add linting by @easy-electrophysiology in #30

Full Changelog: v0.1.0...v1.0.0

This version contains breaking changes. The get_series_data call function now accepts channel_idx as argument rather than getting the channel based only on "Vm" or "Im". The function output also has additional metadata, while the ts field is renamed to sampling_step. Leak channels are now supported.