Fix problems creating new accounts (functions that assumed a user was logged
in when they weren't yet)

• signup.php:

  • use print_page_bot1a() instead of print_page_bot1()
  • use print_page_top2a()

• core/string_api.php
  (string_process_bug_link): make use of string_get_bug_url()
  (string_get_bug_page): return the simple version if the user is not logged in

git-svn-id: http://mantisbt.svn.sourceforge.net/svnroot/mantisbt/trunk@1878 <a class="text" href="/?p=mantisbt.git;a=object;h=f5dc347c">f5dc347c</a>-c33d-0410-90a0-b07cc1902cb9