Improve documentation of Neo #29
Description
Currently, the documentation of Neo is insufficient.
- Some functions are only documented superficially.
- The Neo manual contains only very rudimentary tutorials. They should better guide users on how to properly work with Neo. This is related to tasks that improve the usability, e.g. Powerful filter functions for Neo #23 Functions to work with trials #24 Basic Spiketrain/AnalogSignal operations #26.