Merge pull request #8691 from acapilleri/preload_association

refactoring to_sym of Symbol in preload
replace #flatten with Array()
Merge pull request #8692 from lucasmazza/error-page-css

Cleanup the CSS on the new error page.
Merge pull request #8693 from goshakkk/flatten

Replace #flatten with Array()
Link to the right fork of country_select.
remove unnecessary #dup
Merge pull request #8688 from goshakkk/error-page-toggle

Allow toggling dumps on error page
Merge pull request #8694 from goshakkk/undup

Remove unnecessary #dup
remove another unnecessary dup
do not mutate the options hash (when we do not need to)
ask the form builder for form tag attributes
take into account multipart when calculating tag attributes
do not append a second slash when using
Fix a number of validation/style errors:

 * <pre> is not allowed to be nested inside of <p> elements in HTML
 * Indentation of </p> doesn't match corresponding <p>
 * <p> element not explicitly closed
 * One more </div> than <div>

In each case, the template was fixed to match how a HTML5 parser would "see"
the resulting page.
Merge pull request #8702 from rubys/master

Fix a number of validation/style errors
Fixing closing </p>
Merge pull request #8701 from senny/8700_double_slash_with_trailing_slash

do not append a second slash when using `trailing_slash: true`
CVE-2012-5664 options hashes should only be extracted if there are extra parameters

Conflicts:
	activerecord/lib/active_record/dynamic_matchers.rb
make symbol reference in docs appear as code
Merge pull request #8697 from goshakkk/undup

Remove another unnecessary dup