Add Vm graph and inject current

[Ajstros]

I borrowed some edits from the calibrations branch to set up current injection and membrane voltage capture in the ephys folder with record.py. These edits were removed in 8b171f60d0390df6e13bf2798bd55a7e363b843e so they stay in the calibrations branch until that branch is merged. Below are the remaining changes to be merged into the main daq_v2 branch.

• Add a Vm graph to the updating plot in the record function
• Add current injection to record to simulate cell ion channels opening
• Fix h5 data saving at the end of the recording
• Save all data to h5 instead of just chan_data