Fix 0002993: Read/Write access levels not checked in custom fields

M bug_report_advanced_page.php

• Remove the spacer after the custom fields if no custom fields were printed.
• Make sure that the current user's access level >= required write access level.

M bug_report_page.php

• Remove the spacer after the custom fields if no custom fields were printed.
• Make sure that the current user's access level >= required write access level.

M bug_update_advanced_page.php

• Remove the spacer after the custom fields if no custom fields were printed.
• Make sure that the current user's access level >= required write access level.

M bug_update_page.php

• Remove the spacer after the custom fields if no custom fields were printed.
• Make sure that the current user's access level >= required write access level.

M bug_view_advanced_page.php

• Remove the spacer after the custom fields if no custom fields were printed.
• Make sure that the current user's access level >= required read access level.

M bug_view_page.php

• Remove the spacer after the custom fields if no custom fields were printed.
• Make sure that the current user's access level >= required read access level.

M core/custom_field_api.php

• (custom_field_has_read_access): Default $p_user to null for current user.
• (custom_field_has_write_access_to_project): Check write access based on project id rather than bug id.
  This is needed when adding a new bug.
• (custom_field_has_write_access): Changed to use custom_field_has_write_access_to_project(). Also defaulted
  $p_user_id to null for current user.
• (custom_field_set_value): Changed to check write access rather than read access level before setting the
  value of a custom field.

git-svn-id: http://mantisbt.svn.sourceforge.net/svnroot/mantisbt/trunk@2002 <a class="text" href="/?p=mantisbt.git;a=object;h=f5dc347c">f5dc347c</a>-c33d-0410-90a0-b07cc1902cb9