initial named query refactor in preparation for namedstmt, #16
add NamedStmt support, lots more testing around it...  still no Map support
add tx.PrepareNamed
Merge branch 'master' into named-stmt

Conflicts:
	bind.go
restore oracle binding
move NamedQuery generic functions and deprecate Map variants
add deprecation comments around all map variants for named query execution, rewrite underlying bind functions so they can bind either, add support for maps to namedstmt and namedexec/query
remove tests for deprecated Named*Map functions and instead test that the generic variants handle maps
some small readme adjustments for the named stmt changes