fixed problems with joined inheritance and composite keys

[Powerhamster]

SchemaTool now creates all Id columns not just only the first one.
Insert statement for child entity now contains parameter for additional key columns only once.

[doctrinebot]

Hello,

thank you for positing this Pull Request. I have automatically opened an issue on our Jira Bug Tracker for you with the details of this Pull-Request. See the Link:

http://doctrine-project.org/jira/browse/DDC-2201

[beberlei]

1. What is the problem?
2. What does your solution attempt to fix?
3. Is the schema changed by this?

If the answer to 3 is yes, then this PR is an unacceptable backwards compatible break and cannot be merged at all. I would like to try to understand what problem you see in the current implementation and help you with that instead.

[Powerhamster]

I am using entities with composite keys. By using joined inheritance I discovered that only the first id column becomes part of the derived table. This has been fixed, so that now all id columns are created correctly.
All this id columns become now part of one foreign key contraint.

There should be no backwards compatibilty break. Usage of composite keys with joinded inhertitance doesn't work, so it can't be used be someone. The fix has no effect to inheritance with only a single pk column. This should work as before.

[beberlei]

Ok, I understand the issue better now, thanks for the clarification