Add warnings and errors to ImpactsOutput

[samuelrince]

For #59

[adrienbanse]

Thanks @samuelrince for the nice PR! Much better like this

Just a small comment. Although I completely agree that spamming the user with the logger for the warnings is a bad idea, it still seems to me that the errors should be very easily spotable by the user. A first-time user could try EcoLogits, get nonsense values in ImpactsOutput and miss the error.
--> To me, it should be crystal clear from the welcome page in ecologits.ai that the user has to check himself/herself the errors

[samuelrince]

Yes, I agree with you @adrienbanse, more documentation on the get started should be added! I'm thinking, maybe we can also consider showing warnings and errors in the console the first time they appear and then ignoring them. I'll try to improve this!

[samuelrince]

Ping @adrienbanse if you want to check the new changes on the logging system :)

FYI I am working on an improved version of the documentation on docs/update branch. It will include more info on errors and warnings on the main page.

[adrienbanse]

This is great, thanks @samuelrince

[samuelrince]

Also, ping @cvarrei, logging behavior will change. Warnings and errors related to the impact calculation will be shown only once, but still present in the ImpactsOutput object on the warnings and errors fields. (related to an old issue #65)