Remove .general-sidebar-notes, inline text instead

This removes all "hanging on" sidebars apart from the main reporting a
problem one, interspersing the text in the form instead.
Tweak reporting form i18n and style.

Factor out "(public)" to its own string, and only remove the label top
margin if it's an immediate child (otherwise labels inside divs halfway
down lose their margin).
[Oxfordshire] Lower min-height offset to cover map
Move most 'change location' text to main column.
Remove margin from fieldsets, tidy box sizes.