Create interface for Dataset class, refactor code

[bburlacu]

We should extract the essential requirements for a Dataset object into an interface, which should then be used in the code (mostly DataAnalysis.Symbolic), so that custom dataset objects can be employed in certain use cases.

[bburlacu]

r11571: Commit initial version of IDataset interface and code refactoring.

[bburlacu]

r11572: Merged the Programmable problem projects into the branch, adjusted references and build paths.

[bburlacu]

r11579: Removed unnecessary folders from the branch.

[bburlacu]

r11584: Removed programmable problem from this branch.

[bburlacu]

r11589: Unsealed Dataset class, refactored GetDoubleValues, GetStringValues, GetDateTimeValues methods to internally use the same generic method, added ModifiableDataset class which adds the functionality of replacing, adding or removing rows in the dataset.

[bburlacu]

r11621: Removed SimpleDataset class in favor of ModifiableDataset. Decided to keep the IDataset interface (even though a cast to Dataset is needed in 2 places).

[bburlacu]

r11853: Make Arc storable constructor protected (this change was meant for the trunk version but was accidentally committed in this branch).

[bburlacu]

r12031: Merged trunk changes.

[bburlacu]

r12032: Extended functionality of ModifiableDataset with three new methods: AddVariable, RemoveVariable and ChangeVariableValue.

[bburlacu]

r12105: Merged trunk changes.

[bburlacu]

r12109: Merged trunk changes.

[bburlacu]

r12141:

• Implemented a ModifiableDatasetView which allows values in the modifiable dataset to be visually edited.
• Made SetValue and Validate implementations explicit in the Dataset class
• Added explicit implementations of SetValue and Validate in the ModifiableDataset
• Renamed ChangeVariableValue method to SetVariableValue for consistency

[bburlacu]

r12190: Changed the GetVariableType method so that it also works when there are no rows in the dataset.

[mkommend]

r12247: Merged trunk changes into dataset refactoring branch.

[mkommend]

r12437: Organized code in IDataset.

[mkommend]

r12438: Merged trunk changes into dataset refactoring branch.

[mkommend]

Please implement the change events such as ColumnsChanged, RowsChanged, ... for the ModifiableDataset.

[mkommend]

r12452: Adapted generic GetValues<T> method in Dataset to avoid ToList calls.

[mkommend]

r12453: Changes to reduce the memory consumption of GP.

Profiling the first 20 generations of the "GP - Symbolic Regression" sample showed a reduction of ~ 700MB (30%) of allocated bytes.

Summary for HeuristicLab 3.3 trunk.log			Summary for HeuristicLab 3.3 refactored.log
Allocated bytes:              2,280,452,065		Allocated bytes:              1,577,495,256
Relocated bytes:                 72,310,923		Relocated bytes:                 71,416,397
Final Heap bytes:               258,834,133		Final Heap bytes:               360,013,510
Objects finalized:                    6,476		Objects finalized:                    4,049
Critical objects finalized:           1,697		Critical objects finalized:           1,440
Gen 0 collections:                       18		Gen 0 collections:                       16
Gen 1 collections:                       11		Gen 1 collections:                        7
Gen 2 collections:                        8		Gen 2 collections:                        5
Induced collections:                      0		Induced collections:                      0
Gen 0 Heap bytes:               191,961,295		Gen 0 Heap bytes:               164,683,847
Gen 1 Heap bytes:                15,646,303		Gen 1 Heap bytes:                13,780,491
Gen 2 Heap bytes:                24,997,270		Gen 2 Heap bytes:                22,111,974
Large Object Heap bytes:         11,101,599		Large Object Heap bytes:          7,515,030
Handles created:                    115,616		Handles created:                     99,237
Handles destroyed:                   58,786		Handles destroyed:                   43,106
Handles surviving:  

[mkommend]

r12454: Changed util method CalculateEvaluatedNodesPerSec to cache the rows enumerable.

[bburlacu]

r12489: Made events in Dataset.cs virtual and overrode them in the ModifiableDataset class. Added event handlers for dataset changes.

[mkommend]

r12505: Merged trunk changes into dataset refactoring branch.

[mkommend]

r12508: Minor changes in modifiable dataset.

[mkommend]

r12509: Reintegrated branch for dataset refactoring.

[mkommend]

r12510: Removed branch for dataset refactoring.

[mkommend]

r12511: Sealed ModifiableDataset.

[mkommend]

r12524: Forgot to commit merge infos for dataset refactoring reintegration.

[mkommend]

r12578: Corrected shrink menu item to only consider objects of type Dataset.

[mkommend]

r12702: Merged changes to stable.