Better snippets in the mouseover-layer plugin

Some minor changes in core plugins

Closes #237.

Sidebar now toggled based on media queries only.

Closes #232.

Moved into question page so that it’s not on other pages, and so we can
obtain correct answer count.

Logged out users now get ‘login’ error regardless of user level
required.

Decimals parameter takes effect when compact option is off.

Decimals for non-compact numbers were being incorrectly removed.
Numbers were being rounded twice (123456789 -> 124k not 123k).
Numbers larger than 1 billion were being incorrectly shortened.