clickable tags in search and installed panes

[torkus]

• [x] tags are replaced with clickable buttons
• [x] clicking a tag button filters search results
• [x] tag button is disabled/marked if part of filters already
• [x] tags are added to the search bar on click.
• [x] clicking tag in search bar removes them from search
• [x] clicking a tag in the installed pane switches to the search pane
• [x] tooltips on tags (because they're getting truncated when many)
• [x] bug: navigation buttons have stopped working
• [x] styling
• [x] review
• [x] update CHANGELOG

[torkus]