reset editor when closing the window. fix #30 fix #29

[j-levy]

Even though it deletes and re-creates the editor object, it's a simple enough fix for now.
I also fixed the window size starting too small on macOS 11.4 (now it starts at a comfortable 600x400 with a strict minimum size of 300x200, so you don't get lost with a dialog you can't even see the content of)

[j-levy]

Note: travis builds fail because of a problem in their configuration, I think
If I see the logs, it ends like this:

export PATH='/Users/travis/miniconda/bin:/Users/travis/miniconda/condabin:/Users/travis/miniconda/bin:/Users/travis/.rvm/gems/ruby-2.6.3/bin:/Users/travis/.rvm/gems/ruby-2.6.3@global/bin:/Users/travis/.rvm/rubies/ruby-2.6.3/bin:/Users/travis/.rvm/bin:/Users/travis/bin:/Users/travis/.local/bin:/Users/travis/.nvm/versions/node/v13.0.1/bin:/usr/local/bin:/usr/bin:/bin:/usr/sbin:/sbin:/opt/X11/bin'

export CONDA_SHLVL='1'

export CONDA_PROMPT_MODIFIER='(base) '

Traceback (most recent call last):

  File "release.py", line 15, in <module>

    for job in status['jobs'][:TRAVIS_JOB_NUMBER]:

KeyError: 'jobs'

Note 2: tested and working on Windows 10 21H1 too.

[j-levy]

I also fixed the crash on windows in issue #29