NEW Completely reworked and enhanced the synthetic_test module.

- Added the combime_experiment_results() function which combines the results of particular experiments and draws a plot with the combined results.
- Changed and augmented the base learners (default is now svm_poly3).
- Added the OracleLearner and changed the order of learners.
- Added new testing configurations which work with the pre-prepared testing sets (21 and 22).
- Added new testing configurations (41 -- 44) which run a set of experiments with one changing parameter value (tasks_per_group, task_groups, n, noise).
- Introduced the 'mode' list -- list of strings indicating in which mode the script is to be run (e.g. "run", "testing", ...).
FIX Changed the dependecy of the test module on Orange from hard to soft dependency.