Fix ADODB odbc_mssql issues, fix mssql datadict

• //if ($ty == 'X' || $ty == 'X2' || $ty == 'B') $fnotnull = false; // some blob types do not accept nulls
  +//if ($ty == 'X') $fdefault = false;

These have been commented out as we've made possible values for custom fields as type X: ADODB doesn't allow 'type X' to be not null or have default values as some db's may not support it for some blob types - so far i'm not aware of any issues, and the behaviour of silently dropping DEFAULT/NOTNULL for blobs breaks updates for mssql.

git-svn-id: http://mantisbt.svn.sourceforge.net/svnroot/mantisbt/trunk@5599 <a class="text" href="/?p=mantisbt.git;a=object;h=f5dc347c">f5dc347c</a>-c33d-0410-90a0-b07cc1902cb9