* Also make ErrorF as a global method.

resolve merge conflicts

* hidden decorator kwargs in DataProvider.__init__
* also add unit test for this.

* hidden decorator kwargs in DataProvider.__init__
* also add unit test for this.

* hidden decorator kwargs in DataProvider.__init__
* also add unit test for this.

Change float in test_ConvTrans and test_ConvUnify to real.

The chunks of types in excluded_chunk_types will not be counted in
ChunkEvaluator. This is useful for tasks such as SRL, in which chunks of
type V (verb) will not be taken into account in evaluation.

reference or raw matrix (Matrix & or Matrix *)
contextProjectionForward
contextProjectionBackward
contextProjectionBackwardData
contextProjectionBackwardWeight
classificationError
The mul functions would be updated later.