Refs #9531. Added ComainCreator for FunctionDomain1DSpectrum.
Refs #9531. Added SeqDomainSpectrumCreator with test.
Refs #9531. Setting fit values in FunctionDomain1DSpectrumCreator.
Refs #9531. Added fitting tests.
Refs #9531. Adjusted Fit to make tests work.
Refs #9531. Added test function for SeqDomainSpectrumCreator.
Refs #9531. Added demonstration algorithm.

The algorithms fits the test function to the provided workspace data. Useful for profiling "real world data" with appropriate dimensions (data and parameters).
Refs #9531. Mapping fit weights in CostFuncFitting.

Instead of calling the virtual function getWeights each time fit weights are accessed in LeastSquaresCostFunc, they are mapped once before the calculations.
Refs #9531. Further reduced number of virtual function calls.

Followed Roman's suggestion to make getFitWeights() virtual and remove getWeight as well as calSqrtW from CostFuncLeastSquares.
Refs #9531. Added documentation to domain creators.
Refs #9531. Added check for SeqDomainSpectrumCreator in Fit.
Refs #9531. Cleaned up SeqDomanSpectrumCreatorTest.
Refs #9531. Removed test function and demonstration algorithm.

This is already in the unit tests now and SeqDomainTestFunction and SeqDomainDemonstration don't do anything useful.
Refs #9531. Fixed doxygen warning.
Refs #9531. Created IFunction1DSpectrum interface.

IFunction1DSpectrum is an interface roughly equivalent to IFunction1D, with the exception that it must use FunctionDomain1DSpectrum.
Refs #9531. Integrated IFunction1DSpectrum into Fit and tests

Instead of having an extra property, fit now checks if the fit function can be cast to IFunction1DSpectrum to assign the correct domain creator.
Re #9531. A couple of corrections to make Fit work
Refs #9531. Modified unit test of SeqDomainSpectrumCreator

The unit test now instantiates Fit via the AlgorithmManager.
Merge branch 'feature/9531_SpectrumSeqDomainCreator' into develop