Add index and primary key output to the sqlite schema writer backend.

[phoyd]

I needed mdb-schema to export the indexes for the mdb databases I want to migrate, so I've added that. This is very straightforward, except that sqlite3 does not support ALTER TABLE PRIMARY KEY . Therefore mdb_print_schema inserts the PRIMARY KEY constraint directly into the table definition.

Tested with a dozen databases from my project, each with ~180 Tables and 200MB size.

[evanmiller]

Thank you for the contribution!