Fixes #14, where the blank menu appears. This was due to the folder where the list of current spaces was created sometimes not existing, causing the write to fail. Now if the folder doesn't exist, it makes it on launch.
Addresses #15 (not a perfect solution). Previously it would just randomly guess which monitor was which. Now it tries to figure out which monitor it is based on the number of monitors, and which one is selected. If it works, then it keeps that same order. If it doesn't, then it falls back to the order that it was in the last time that it worked.
Added in support for 'ESC' closing the renaming window