UI Improvements

[CezaryDanielNowak]

Hi,

• main page: There should be a list of recent git repos (localStorage?)
• modified files view/commited files view: File paths should be selectable (a instead of buttons)
• "Amend last commit" still have old "✓" sign.
• there should be "branch" dropdown for easy branch change
• there should be "undo" button for lots of actions (remove file)
• there should be option "discard change in this line" (eg. if you want to remove console.log)
• stash: There should be a option for preview stash content.
• file preview in commited files log is not scrolling horizontally
• ungit version in top area should be linked to https://github.com/FredrikNoren/ungit