Simplify client-side result customization

The issue was that search results from other providers (contacts,
calendar, etc.) were unformatted, like 'event' or 'contact', while the
built-in event types (folder, file, etc.) were being modified by custom
result functions to something like 'Files' or 'Folders'. The fix is to
capitalize and translate all result types by default. Custom formatting
is still allowed (and example documentation has been added) but the
built-in result formatters where now unnecessary and were removed.