strings.py: as_*table(): Added ustr param to override the method (by default ustr()) used to convert each value to a string

sql_gen.py: MockDb.esc_value(): Use new strings.repr_no_u()

strings.py: Added repr_no_u()

sql.py: clean_name(): Also remove '`' (which is used by MySQL)

sql.py: esc_name_by_module(): Use new sql_gen.esc_name()

sql_gen.py: Added esc_name() and use it in MockDb.esc_name()

sql.py: next_version(): Use special chars in version part of name string for clarity

sql.py: mk_insert_select(): embeddable: function_name is first line of query for clarity, and to reduce length from including the column names. This also fixes the problem of double quotes around column names in the previous function_name.

sql.py: esc_name_by_module(): Double embedded quotes to escape them instead of removing them

sql.py: put_table(): Use "-" to separate temp table suffixes from into table name