Open collection with last used environment

[Arctomachine]

Problem: when I start app and open collection, it loads in "no environment". So I have to manually select environment from list (even if there is only one in this collection) to use variables from it - which I used before closing app and intend to keep using again now as I continue to work where I left off last time.

Simple solution: save which environment was used for this collection last time, use it when opening again. Pretty sure in many cases the one that was used before is the one that is expected to be used again - especially in collections with only one environment.

Another solution: global environments (#115) and/or support for variables in default "no environment".