[FeatureRequest] add new node to generic logic NeedToLearnNewSpells

[Bia10]

The interaction with the trainer will be similar to merchant via Lua hacks :/

• A very stupid solution that visits trainer every level up and assume having more cash then price of services

• This is implemented in implement a very crude and dumb skill training #88

Some more refined spell training

This should use the Lua API for trainer:
BuyTrainerService(), GetTrainerServiceInfo(), GetTrainerServiceCost()

• LearnSpellByName()

• LearnSpellById()

• LearnAllSpells()

• CanLearnNewSpells()

• CanImproveSpellsRank()

This leads to question:
The question remains where are we gonna check for these data from? prolly hold it in external LiteDB or in json/xml/csv