Squashed commit of the following:

commit a226efe4bb24a5e0ffe746197b4236c20589df2c
Author: Clemens Frahnow <clemens24@web.de>
Date:   Sat Jan 4 18:55:40 2014 +0100

    load tables from context

commit dbbc757fbc594f5231e0d2ba83ab133392edee80
Author: Clemens Frahnow <clemens24@web.de>
Date:   Sat Jan 4 18:45:11 2014 +0100

    fix query19
Bugfixes / Improvements to DynamicPriorityScheduler

* RadixJoin no longer caps the probe phase to 24 instances.
* A new fitting model for the TableScan has been added.
* A new fitting model for the RadixJoin has been added.
* Added missing code for changeDependency + regression tests.
* Added some explanation for the model used.
Merge pull request #285 from kaihowl/pullrequest/dynamic

Bugfixes / Improvements to DynamicPriorityScheduler
Merge branch 'master' into feature/TPCCHQueries