First try at improving the README, more to come
Compact screenshot
Add a bit of FAQ
README: typo
Contribution notes
Adapt text to changed screenshot
Fix some wording issues
Set port variable instead of placeholder

Suggesting a port in the placeholder can be confusing, as it may
lead people to believe that this value will be sent to the server
while in fact it will not be.

Fix #324
Merge pull request #320 from glowing-bear/docs

Improve README
Merge pull request #325 from glowing-bear/fix_default_port

Set port variable instead of placeholder