The DBI and some drivers make a distinction between an undef username or password vs an empty string.

In RT #93128, TIMB recommends using undef as the default value.
config file for dzil
let dzil setup $VERSION
remove files generated by dzil
Mention Test::Database::Tutorial in a place it will be seen

Fixes RT #78337 by Mark Lawrence
Merge branch 'dzil'
move the misleading quote in a HISTORY section

fix RT #64528
link modules names in the documentation
POD fix
improve linkability of the documentation

this is done by moving all methods under a =head2 heading, and showing code examples below
remove unneeded files
Changes for version 1.111