add pgup/pgdn keys and fix history in multiline edits
Keep core buffer visible with 'only show unread'
Merge pull request #447 from glowing-bear/unread-only-show-core

Keep core buffer visible with 'only show unread'
Scroll to correct position when fetching more lines

Fixes #406
embedded content: check if scrollIntoViewIfNeeded vendor method is available
Merge pull request #455 from ailin-nemui/ifneeded-conditional

embedded content: check if scrollIntoViewIfNeeded vendor method is available
Merge pull request #448 from glowing-bear/fix-scrolling-fetchMoreLines

Scroll to correct position when fetching more lines
Merge pull request #445 from ailin-nemui/up-down-pgup-pgdn

add pgup/pgdn keys and fix history in multiline edits
Create dark theme by extracting theme settings from glowingbear.css

* Remove style.css as those values should be themable as well.
* Update urls in index.html to link to dark theme by default
Provide a way to change the theme in the settings

* Selected theme is dynamically loaded
* Preferred theme is stored in the settings.
* Default theme = dark
Provide a way to change the theme in the settings

* Selected theme is dynamically loaded
* Preferred theme is stored in the settings.
* Default theme = dark
Add light theme
light-theme: darken most colors by 50% and add it to theme manager
[light theme] make the background lighter
[light theme] set highlight colour to something readable
[light theme] improve readability of default grey colours
fix: fix the notification colour again
[light theme] make default text color readable
themes: fix some base colours
style option control in light theme