Fix annotations for QAbstractItemModel signals

[james-emerton]

Update the stubs for QAbstractItemModel to mark all the signals as the correct type.

[bluebird75]

Nice stuff. You are missing the following signals :

• columnsMoved
• columnsAboutToBeMoved
• rowsMoved
• rowsAboutToBeMoved

Could you add them to your PR ?

If you could also add one file in the test directory that would be nice.

[bluebird75]

Equivalent changes have been merged as part of PR #162