Fix for #12

Quick fix of moving focus.

• Improved move focus. #8
• Config keybinding duplication detection. #9
• A few bugs fixed.

• Added sorting tray items by their titles #7
• Fix focus movement behaviour
• Now sends about_to_show to the items, which may not show their menu without it #4

• Fix dependency issue which prevented installation with cargo
• Update system-tray lib to 0.8.0 with a few bug fixes.
• Update all the other dependencies in Cargo.toml

• Add column restricted layout
• Add configurable keybindings

First release.

• Configuration file
• Trees view of menu options