add support for whitematter ecube

[leoscholl]

things to implement:

• datasource
• arduino dio

[leoscholl]

dio (NI) added in 24c1fe36e19343eb0bebf683c32082d63b7f42ec datasource added in 8e4f6f25037e94bd68a0fd541d6620f56469d0a2

also need to implement:

• filtering and detecting spikes
• loading files
• decoder training (should try to refactor so we don't have to write so much code)