Fixes for Darwin related environment encoding problem and failure to …

…stop web server.

Merge branch 'tmontes-fix-editor-margin-connect-test'

Merge pull request mu-editor#739 from mu-editor/remember-path

File dialog will remember path last used.

Update to work with latest briefcase version for OSX builds.

Fix names in Appveyor (doh).

Release Candidate 1 (now with added MicroPython).

Update CHANGES for upcoming beta 17 release.

Bump version to beta.16.

1.0.0.beta.15

Bumped version number.