Separate the curve fitting algorithms into a CurveFitting library

[NickDraper]

We need to split the curve fitting algorithms into a separate curve fitting library.

This entails the following:
- Create a new CurveFitting project in the mantid visual studio solution
- Copy all of the settings (for debug and release) from the algorithms project
- Remove any settings from algorithms that no longer apply (eg. GSL link lines)
- Move the cpp and h files over and alter any namespaces etc
- Edit the sconstruct file to add your project to the list (about 1/2 way down).
- Add a sconscript file (copy and edit from algorithms.
- Check it all build in VS and scons.
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Keywords: curve fitting

[NickDraper]

This issue was originally trac ticket 193