v2.1.0

Notable fixes in the style manager page:

• fix import/export
• show actions as icons or flat labels (by default) or buttons after clicking the triangular expander icon on the left
• reorder buttons as Sync, Import, Export and show the status underneath the Sync button

Known bugs (fixed in the test build):

• the [x] UserCSS checkbox doesn't work in the style manager, please use the one in the popup
• #1862: Stylus installer incorrectly intercepts .user.css pages like this one, see the linked report for workarounds.