can create extensions
can create sequences, refactored quoting of idents
added sequence creation
create table columns with not null constraints and literal or constant
default
create unique constraints
create foreign key constraints
savepoint
created factory interface for Constant
switched to a factory pattern for Extension.
switched to factory pattern for Sequence
switched to factory pattern for table
added factory pattern for extension data types and functions
created factory interface for PrimaryKeyConstraint
added factory interface for UniqueConstraint
switched to factory interface for ForeignKeyConstraint
added factory pattern for TableColumn and TableColumn defaults
switched to factory pattern for Database
savepoint
renamed directory from postgres->relational
renamed directory from postgres->relational