Fix the obvous memory leaks shown by cppcheck

[Martyn Gigg]

When setting up the Jenkins cppcheck it gave some very obvious memory leaks

Code/Mantid/Framework/CurveFitting/src/Convolution.cpp	86	memleak	error	Memory leak: xr
Code/Mantid/Framework/DataHandling/src/SaveToSNSHistogramNexus.cpp	594	memleak	error	Memory leak: tof_data
Code/Mantid/MantidPlot/src/FFT.cpp	101	memleak	error	Memory leak: amp
Code/Mantid/MantidPlot/src/Interpolation.cpp	182	memleak	error	Memory leak: ytemp
Code/Mantid/MantidPlot/src/Interpolation.cpp	182	memleak	error	Memory leak: xtemp
Code/Mantid/Vates/VatesAPI/src/vtkThresholdingHexahedronFactory.cpp	284	memleak	error	Memory leak: pointIDs
Code/Mantid/Vates/VatesAPI/src/vtkThresholdingHexahedronFactory.cpp	284	memleak	error	Memory leak: voxelShown
Code/Mantid/Vates/VatesAPI/src/vtkThresholdingHexahedronFactory.cpp	284	memleak	error	Memory leak: pointNeeded
Code/Mantid/Vates/VatesAPI/src/vtkThresholdingQuadFactory.cpp	200	memleak	error	Memory leak: pointIDs
Code/Mantid/Vates/VatesAPI/src/vtkThresholdingQuadFactory.cpp	200	memleak	error	Memory leak: voxelShown
Code/Mantid/Vates/VatesAPI/src/vtkThresholdingQuadFactory.cpp	200	memleak	error	Memory leak: pointNeeded
Code/Mantid/Framework/CurveFitting/src/Convolution.cpp	196	mismatchAllocDealloc	error	Mismatching allocation and deallocation: tmp
Code/Mantid/Framework/DataHandling/src/SaveISISNexus.cpp	363	mismatchAllocDealloc	error	Mismatching allocation and deallocation: buff

They are easy to fix as cppcheck gives the exact line where the leak happens.

[Martyn Gigg]

Refs #4011. Fix some obvious memory leaks picked up by cppcheck.

Changeset: edc416def81f74aed888168d48aed945d58b66a3

[Martyn Gigg]

Refs #4011. Fix more obvious memory leaks picked up by cppcheck.

Changeset: e87573c9ad4917b478bfea0827f1ee6eb04eb54a

[Stuart Campbell]

This ticket has been transferred to github issue ​4858