adjust min/max scaler

change minmax scaler behaviour to scale values between -1 and 1 instead of 0 and 1. This will make #300 (closed) much more easy to execute.

added enhancement forthcoming labels

added Doing label and removed forthcoming label

created merge request !293 (merged) to address this issue

mentioned in merge request !293 (merged)

mentioned in commit 5f9fdceb

added .done label and removed Doing label

added merged in Develop label and removed .done label

closed with merge request !318 (merged)

mentioned in commit 1634c669