Remove spurious test.
Implement cloneDynamic() for {First,Second}DerivExternalFunction.

Since the method was not implement, the method of the parent class was used.
This was leading to wrong results in the context of Ramsey Policy (basically
derivative operators on external functions were dropped from FOCs).
Cosmetic renaming for consistency between DataTree method names.
Introduce a new abstract class for external function nodes.

This fixes the following bugs:

- 1st and 2nd ext fcn deriv nodes were incorrectly added to
  DataTree::external_function_node_map, because of the chaining of
  constructors.

- the following methods of FirstDerivExternalFunctionNode were not overloaded:
  toStatic(), buildSimilarExternalFunctionNode()

- the following methods of SecondDerivExternalFunctionNode were not overloaded:
  toStatic(), buildSimilarExternalFunctionNode(), compile(),
  compileExternalFunctionOutput()
Fix crash when the model contains 1st or 2nd ext fcn deriv nodes.

In the case where the external function computes itself its derivatives, the
TEF terms were not always created before being used, hence leading to a
preprocessor crash. This problem could only happen with ramsey_policy, because
otherwise the model does not contain derivatives of external functions.
Fix comments in header of dynamic and static files

Columns and rows were confused
submodule update: dmm
doc: sbvar_identification stub, #237
Merge pull request #636 from JohannesPfeifer/preprocessor

Fix comments in header of dynamic and static files
Change fields in options_ for {irf,moment}_calibration.

Ref #267
Allow ranges in lags/periods specification of {irf,moment}_calibration.

Ref #267
Provisions for MATLAB 8.3 (R2014a).
ms-sbvar: add missing 's' flag to rmdir
Add info about constants to dsge_likelihood.m header
Clarify OSR in manual
Correct placement of @end example in manual
Clarify description of histval for stochastic simulations
Filter out more pathological cases in osr1.m
Fixed bug. Concerns a hidden feature (initialization of the posterior kernel from the prior mode instead of the prior mean).

(cherry picked from commit 90dc33764de443ee7c1063f8d165510756d70f89)
Removed useless line.

(cherry picked from commit 7482c9b8208635f6049d945a404c925aa8b2e6d4)