This commit adds time correction to the Muon loader. As the histogram data was loaded using the LoadISISNexus algorithm the time zero needed to be applied afterwards.

This commit updates the unit test for the Muon Nexus V2. This was required as the example file has changed since the test was written.

This commit creates the following:
-LoadMuonNexus3 algorithm
-LoadMuonNexus3Helper file
-LoadMuonNexus3Test file
-Adds a MuonV2 file to the test data
This commit also implements the detector grouping calculation.