Update to the Load algorithm to allow running solely to discover the concrete loader type. Also updated workspace property to respect the optional flag in other cirumstances. Re #2329

Fixes #2074: run_start property when loading SNS files will allow the right instrument definition to be loaded.

Created a pool for parametrized detector objects to avoid excessive calls to the new operator in multi-threaded loops. If a cached object already exists and is unique then it's memory is reused rather than reallocating another object. This alleviates some of the locking within threaded loops that was impeding the scaling with the number of cores. There is still something to done with instruments but an issue remains with plottable components. Re #2276

Fixes #2324: Call to sortAll before CompressEvents speeds things up from 80 to 30 seconds in one example (95 million event list). Same thing in ConvertToMatrixWorkspace. Nicer reporting.

 Fixes #2277: A million tests for every possible permutation of multiply and divide workspace. Whew!

Needed to use RectangularDetector notation in sans2d IDF

re #2318

Fix for problems with keeping position and rotations parameters in sync with the ParameterMap's cache when they are set in isolation to the ParameterMap. Now, set can only be called by the ParameterMap and all changes to parameters, whether addition/replacement should use the addV3D, addDouble etc members of the ParameterMap. Re #2276

Refs #2187: Added some calls to release free memory if you linked against TCmalloc; commented out for now.

Revert a change from some time back regarding how grouped detector positions are calculated in Absorption corrections routines. Small change in numerical result (for the better), big change in speed. Also a small refactoring in detector code that was less small in its impact on tests. Re #2276.

refs #2231 - GroupDetectors "average" option. Hopefully with unit test. Sorry, can't run tests locally so they're quite likely to fail I think.

Removed check for the executable name from the ConfigService. It now either uses the path pointed to by MANTIDPATH or the executable's directory if the former is not set. Also renamed a couple of functions relating to this so that it is clearer what their return values point. Re #2256

Load() now has an extra optional property, the entry number to load in a multi-period file. Currently only ISIS Nexus files support this re #2209

Remove final reference to the MERLIN file in the AutoTestData directory. Switched to using a much smaller MARI file for the RAW part of the SetScalingPSD test. Removed unused MERLIN and MARI files from AutoTestData. Re #1911