Rewrite the code to work with 15 minute data

[HuggeK]

EDIT: I was thinking about this and we could maybe write the code in a way that it works in 15 min chunks so it will work in the future but also support the legacy 1h resolutions and price data by taking the date when the switch happened and Switching to a different price fetch on that date. Maybe it is to complicated by doing that?

[HuggeK]

I have thought about this and I can´t see a reason to still support 1h time invervalls becuase it is hard to compare a marked wich operates in different resolutions. So just make sure that the user inputs 15-min data so we get the right analysis. Will make more sense after this summer when it have been implemented in all countries. Would be instresting to gather together which date all the countries shiffted to PT15M resultion.

[HuggeK]

(My guess) ENTSO-E api was used becuase you can fetch more data in one request than the sourceful api which is a maximum of 10 days historicaly, which doesn´t tax the server or proccesing as much.