Split data layer to separate class

[konard]

1000 RUB reward can be claimed by anyone who completes this task.

It can be named DataService or DataLayer or DataApi or something better.
All usages of BetterBotBase should be removed from the main (V) class.
These usages should be moved to a separate class (with separate file).

[dry71]

https://github.com/linksplatform/Bot/blob/DataService/python/DataService.py

[konard]

Rewards are:
700 RUB for @dry71
300 RUB for @Ethosa