Fix breakage in processing (or not) of :col-name slot argument

When computing the column names to use for insert/update methods on
dao instance consider the class's column-map and not just the slots'
names.

When building up s-sql forms in the dao readers/writers make sure to
use :raw for the column names (which we have as strings and not
symbols)
Don't supply a name to pomo:with-transaction if we don't intend to use the transaction binding.
Refactor with-(transaction|savepoint|logical-transaction) into macros+call-with functions.

This patch makes no functional changes however it is now possible to
trace, using plain old cl:trace, the transaction/savepoint stacking
macros.