Schema: add unique index on location, foreign_key
Schema: use specific foreign key constraints

MySQL does not support inline REFERENCES specifications.
Schema: set type TIMESTAMP for datetime column

MySQL does not allow DEFAULT CURRENT_TIMESTAMP for INTEGER.
Schema: add Makefile to convert to MySQL syntax

The only difference so far is the spelling of AUTO_INCREMENT so the
Makefile simply substitutes it.
Add a module to read a configuration file
Avoid type as a variable name
Add MySQL access class