Makefile.PL updates for DBI

Hi,

I'd like to update Makefile.PL of DBI like I did for SQL::Statement in 
revisions 13845 and 13970 (see repository at 
https://svn.perl.org/modules/SQL-Statement/trunk):

- Add a WriteMakefile1 function, which checks features of available
   EU::MM, and disable some unavailable features
   In opposite to SQL::Statement I would prefer drop recommended
   dependencies, instead of merge them into required.
- Warn in case of conflicts (initialized with currently known to me):
   * SQL::Statement <= 1.27
   * DBD::CSV <= 0.29
   * DBD::AnyData <= 0.09

Any dissenting opinions?

Jens