Icons preloading introduced in 247755c5 overrides entire background
property, not just background-image. On 2x screens (and anywhere else
where svg icons need to be scaled) icons need property `background-size:
contain` to be displayed correctly. This previously came from
`.icon-css` class but have been overriden by code generated in
`svgicon`, so to fix this, these properties need to be added to the
`svgicon`.
- Rollback all redundant changes made in the last few months
- Introduce `contextPane`
- Show child notes in the notes pane
- Fix splitter styling
- Various bug fixes
- Fix contextPane switching and states persistence
- Persist reader sidebar open/close state
- Fix bottom pane placeholder updating concurrency issues
- Fix toolbar placeholder width updating
- Display titles for split button
- Fix toolbar position when switching tabs
- Add PDF tab loading cover
- Improve notes and citations insertion
- Clean up and refactor code
- Fixes and cleanups to PDF reader
- Added icon-button UI code for the menubutton
- Upgrade to React 16 to allow non-standard attrs, such as `tooltiptext`
to support XUL tooltips
- Add i18n support for React UI elements
- Update tests for reactified tag selector
