Checkboxes lost it's status if error occurred (e.g. invalid handle) when adding a new page type, now checkboxes are able to remains checked after error.
Merge branch 'fix/page-type-add/checkbox-states-disappears-if-error-occurred' of https://github.com/ojalehto/concrete5 into merge_preserve_checkboxes_new_page_type_valdiation_error
Add is_array check

Add is_array check for `$_POST['akID']` to prevent any possible edge
case where that returned an int etc
Merge pull request #1310 from mkly/merge_preserve_checkboxes_new_page_type_valdiation_error

Merge preserve checkboxes new page type valdiation error