Minor UI enhancements
Check for repeated recipient IDs
Probably fix #153
miniLock now stops when passed not valid file
Fix #150
Improved comments of codebase
Update README.md
Update README.md
Update README.md
Update README.md
Fix #160

If sender is the same as the current miniLocker no red
warning are showed. This should be nice for first time users,
as reported by them.
Merge pull request #156 from giuscri/#111

Minor UI enhancements
Merge pull request #157 from giuscri/#123

Check for repeated recipient IDs
Merge pull request #158 from giuscri/#153

Probably fix #153
Merge pull request #159 from giuscri/#150

Fix #150
Merge pull request #161 from giuscri/#160

Fix #160