disable vechai because of IncompleteRead bug

see #2
don't hijack modkey-clicks

User might want to Ctrl-Click or Shift-Click to open link in a new
tab/window. Don't interfere with that (or any other modifier keys, just
to be on the safe side).
don't reload page when searching

use router.setRoute() instead of window.location.href to prevent a
normal page reload.
correct cached data key for search
make bottom ActionBar identical to top
make SeriesBookmarks show unread chapters only
properly remove series bookmark

Make it similar to removing chapter bookmark: actually removing the
series item out of the array instead of setting its state to "removed"
like before.

Also show "removing" status on button.
give series descriptions unique keys

to suppress react unique key warning
refactor series_bookmarks

Split different parts of SeriesItem into separate functions for clarity