Clean up some error-handling messages a bit, particularly as relate to TitleBlacklist.

Clean up some error-handling messages a bit, particularly as relate to TitleBlacklist.
* Hook-generated error messages should be strong class="error" on moving a page, just like system-generated errors.
* For consistency, "You do not have permission to do that, for the following reason:" should be displayed even if there's only one error message.
* Add a <div class="permissions-errors"> for a single error displayed on editing a page, akin to the <ul class="permissions-errors"> already present.
* In TitleBlacklist, errors should be inline and unstyled; otherwise they'll display inconsistently when added to lists, styled externally, etc.  Using <code> for the matching regex is better than using bold/italics.  I *did not* change all the different languages, only English.