fixup font-family and font-size setting glitches

Replace fontSize placeholder by default value. Placeholders should be used
as suggestions, not effective values.

Remove spurious default value for fontFamily (it is defined right below)
Merge pull request #433 from glowing-bear/fix-font-size-glitch

fixup font-family and font-size setting glitches
Don't capitalise host name

Fixes #439
Merge pull request #441 from glowing-bear/connection-form

Don't capitalise host name
Re-enable "fetch more lines" after trimming lines on buffer switch

Fixes #404
make the help more pleasant by adding kbd tags
Merge pull request #444 from ailin-nemui/help-kbd

make the help more pleasant by adding kbd tags
Properly Show and hide the sidebar on mobile layout when using Alt+g
Merge pull request #446 from ailin-nemui/show-sidebar

Properly Show and hide the sidebar on mobile layout when using Alt+g
Merge pull request #442 from glowing-bear/fix-line-fetching-after-switch

Re-enable "fetch more lines" after trimming lines on buffer switch
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