Refactor climate match function: use help-subfunctions

[damianooldoni]

From #77:
Climate match function is way too long. Splitting in subfunctions will help readibility and debugging: future-you, the maintainer (that's me 😮 ) and anyone else trying to understand the workflow will be grateful. Notice that these subfunctions can be written in the same R file, just append them below the "main" function. For example, the leaflet part is clearly something you can put in a subfunction, isn't?

[damianooldoni]

I think we can close this issue as we will remove this function, see #122. The refactoring will be done in that package.