All zoom buttons run through same handler now.
They no longer take only the delta of the current zoom and desired zoom-- they take the actual desired zoom.
calculateZoom is now calculateChange, to help get the desired delta.
Removes icons as components, uses mask-image instead.
Sets a size on the .fac icons to 1em so by default they are 1em and retain their aspect ratio.
rename the icon files for consistency.
Reintroducing handlePageChange() method to handle the page input separately from the scroll function. It tests the regex pattern on the string, parses to integer, and sets pageNum state.
scrollToPage also now sets the pageNum state after performing the scroll so the input box matches the new current page.
This was previously in the .pageInfo widget, probably not for any good reason, but I'm moving it to the popups div for probably not a good reason.
It's used to get the parent .pane div, and pull its `height` value which is then passed to the `.brewRenderer` div to set the height.
I tried alternate methods that would make this obsolete (CSS methods mostly), but due to some complexity am just ditching those alternatives and popping this sucker into `.popups` for now.
stylelint has a problem with the `:horizontal` pseudo selector in brewRenderer.jsx, which is being used to apply some styling to the custom scrollbars. As far as i can tell, the selector is not standards-track, so that is probably why. Not sure if we want to adjsut our stylelint config to allow it?
Moved the single-line handler to operate directly in the onChange handler of the input that is calling it.
Considered doing the same with handleZoomChange, but that handler is used by two buttons rather than just one.
handleScroll is replaced by getCurrentPage(), which effectively does the same thing. The math is slightly different, though very similar, and result seems to be the same.
