- Allow implementing modules that use exportable tables to use hook_schema() (and thus change management via hook_update_N) on data managed tables.
- Make CTools a hard dependency. It has been a matter-of-fact dependency before, requiring it simplifies code.
- Add a .install to data_ui_test module: required for simpletest to set up and break down cleanly.

All tests passing. However, there remains a problem with occasionally illegal table definitions generated by fields generator in data_ui.test.

Only create field if random values yield result, throw error when random value source array is empty.

Fix race condition when exposing schemas, remove stray error output, unserialize schema info when not using ctools.

Move data_alter_table() back into data_ui as it requires too specific arguments - clearly a helper function.