Implement simplex optimisation if derivative is not available

[Nick Draper]

If the derivative of the fit function has not been defined switch to using the simplex optimisation in GSL.

The NotImplementedException could be thrown and checked in the base class if the derivative function has not been overridden.

[Anders Markvardsen]

(In [2570]) Implemented simplex algorithm, which will run if no derivatives are available. Also unit test added to Gaussian1Dtest which tests that with good accurately the simplex and none simplex algorithm refine a test example to the same solution. Refs #610.

[Anders Markvardsen]

(In [2571]) Removed a few code and doxygen warnings. Refs #610.

[Anders Markvardsen]

(In [2607]) Added some additional code doc for Fit1D. Refs #610.

[Anders Markvardsen]

(In [2610]) Additional code comments and warning if number of data points less than number of parameters. Refs #610.

[Anders Markvardsen]

(In [2617]) Russell located memory leak problem in Fit1D. This commit is to test to see if uncomment code related to this leak will fix the problem on the Linux build server. Note this will temporarily turn off the option to do simplex fitting. Refs #610.

[Anders Markvardsen]

(In [2620]) To get around memory leak problem for now introduced overwriteDefaultSettings() to Fit1D, used to overwrite default algorithm settings. Refs #610.

[Stuart Campbell]

This ticket has been transferred to github issue ​1458