Refs #9059

Just checking that it's not empty can mean that filling it is in
progress, so we need to enter the critical block if that's the case.
This shouldn't have much (any?) performance implication as size(),
like empty(), takes constant time.

Should stop GetDetOffsetsMultiPeaks performance test from failing
sporadically.

Need for this highlighted by performance test failure (GetDetOffsetsMultiPeaksTestPerformance).

And also a custom dialog for it.

also indentation fix to SortDialog

refs #3641. First pass. It is known that the exact column list for the underlying tableworkspace is not confirmed.

Refs #3590: MDEWFindPeaks: AppendPeaks option, replace output if not checked. Also sorting output by bankname and intensity.

mainly some changes to itableworkspace + column in connection with writing tables to nexus. re #2425

Refs #2840: PeaksWorkspace rewritten to use a vector of Peak objects instead. PeakIntegration should be checked (no test). Added an algorithm that creates a simple empty PeaksWorkspace, for testing and perhaps future use by Andrei.