sql.py: esc_name_by_module(): preserve_case defaults to True

sql.py: mk_select(): Escape all names used (table, column, cond, etc.)

sql.py: esc_name_by_module(): If not enclosing name in quotes, call check_name() on it

sql.py: mk_select(): Support literal values in the list of cols to select

sql.py: mk_select(): Don't escape the table name, because it will either be check_name()d or it's already been escaped

sql.py: Added mk_select(), and use it in select()

bin/map: Always pass qual_name(table) to sql.select(). This is possible now that qual_name() can handle None schemas.

db_xml.py: put_table(): Take separate in_table and in_schema names, instead of in_table and table_is_esc, because the in_schema is needed to scope the temp tables appropriately

sql.py: qual_name(): If schema is None, don't prepend schema

bin/map, sql.py: Turned SQL query caching back on because benchmarks of just the caching on vs. off reveal that it does reduce processing time significantly. However, there is a slowdown that was introduced between the time caching was added and the time the same XML tree was used for each node, which was giving the false indication that the slowdown was due to the caching.