Extract function
Configurable output: echo area

Allow to configure the destination of the translation output. Default is
pop up buffer. Implemented one is the echo area.
Remove spaces at the end
Pop-up, echo area and pop up buffer output targets
Fix output
Remove surplus code
Fix unit tests
Fix formats
Rename functions
Extract function
Code refactoring
Fix mistake
Extract buffer insert translation
Pretify the code
Fix doc strings
Fix documentation and doc strings.
Fix translation listening
Rename pop-up symbol, add note about `max-mini-window-height`
Fix unit tests
Fix integration test