I started playing with the custom field stuff tonight and these are the fixes I had to make to get it working. I also cleaned up the manage_* pages a little.

• manage_proj_custom_field_add_existing.php:
  • use gpc_* to get form fields
  • custom_field_bind() errors if there's a problem so there's no need to display our own error
• manage_proj_custom_field_add_new.php:
  • use gpc_* to get form fields
  • use is_blank() instead of ==''
  • add $t_ prefix to $duplicate
• manage_proj_custom_field_delete.php:
  • use gpc_* to get form fields
  • remove unneeded use of $t_affected_projects
  • we can't print $query since such a variable doesn't exist. Also custom_field_delete() errors itself.
• manage_proj_custom_field_edit_page.php:
  • use gpc_* to get form fields
  • correct spelling of sequence as 'seqence'
• manage_proj_custom_field_remove.php:
  • use gpc_* to get form fields
  • custom_field_remove() errors if there's a problem so there's no need to display our own error
• manage_proj_custom_field_update.php:
  • use gpc_get_bool() to get f_advanced
  • correct spelling of sequence as 'seqence'
  • custom_field_update() errors if there's a problem so there's no need to display our own error
• core/custom_field_api.php
  (custom_field_ensure_name_unique): new function that call custom_field_is_name_unique() and errors if it returns false
  (custom_field_create): make sure the name is unique before creating a new field
  (custom_field_bind): move dbprepare* calls to top of function for clarity
  (custom_field_update): use db_prepare_bool() for the advanced field
• lang/strings_english.txt
  (s_custom_field_seqence): correct spelling of sequence as 'seqence' (in variable name and contents)
  (s_custom_field_type_enum_string): correct spelling of enumeration as 'enummeration'
• lang/strings_german.txt
  (s_custom_field_seqence): rename to s_custom_field_sequence (spelling error)

git-svn-id: http://mantisbt.svn.sourceforge.net/svnroot/mantisbt/trunk@1646 <a class="text" href="/?p=mantisbt.git;a=object;h=f5dc347c">f5dc347c</a>-c33d-0410-90a0-b07cc1902cb9