Remove multiple database configuration per environment

[jcaillon]

Objective

Delete the "List of databases" feature, only leave "extra connection".
Accept -pf in the connection field.
Convert existing values from the Dict<> of "list of database" to -pf.

Why deleting this ' feature '

I need to simplify this ui because i want to make this page self generated (as the options pages).
Also, if you want to handle several db, you are supposed to create several environment. I admit that i'ts not very handy at the moment but it will change soon.