Refs #2898: Doxygen fixes. Added a doxyfile for making Doxygen but excluding MDAlgorithsm and MDDataObjects since they overwhelm the results.

Refs #2831, #2830: Coordinate transformation that measures the distance (squared) between an event and a point.

- Refs #2835: Added a MDDimensionStats object that calculates mean and approximate variance of positions.
- Refs #2835: Implemented a binary-tree style splitting for MDEventWorkspaces (MDSplitBox) as an experiment to replace MDGridBox.
- Added Utils::NestedForLoop routines.
- Refs #2711: Improved MDEventWorkspace binning speed by approximately 20 through better scheduling. Memory use is also much lower.
- Refs #2818: Fixed compiler warnings for MDEvents and MDEventsTest (as of last ~Monday with fewer warnings flags).
- More flags added to class_maker.py

re #2817 Components for unity builds/cmake. Tested on Linux ubuntu 32 and 64 bit. Not yet windows compatible.
Build time is half!, would be even quicker with MantidPlot sorted for UnityBuilds.

Refs #2751: Added stub for Fake MD data algorithm. Made properties report the type they expected when you give the wrong value.

Refs #2711: Added an Algorithm to create MDHistoWorkspace. Added Utils namespace to put some things that fit nowhere else, namely a nested for loop helper. Added a helper for MDEventWorkspace creation for tests.

Refs #2016: MDEventWorkspace factory to create MDEventWorkspaces of a given number of dimensions. New algorithm for creating an empty MDEventWorkspace.