Port UserSubWindow to use PythonRunner object. Refs #7468

Isolates the code that does the python execution and output capture.
Add logging to PythonRunner for easier debugging of interface code.

Refs #7468
Move ConvertToEnergy python code to new API.

Includes Indirect.cpp helper class.
Refs #7468
Fix spectra plotting option on Indirect SofQW GUI. Refs #7468
Move IDA code to use new python API.

Includes IndirectDataAnalysis.cpp & CalcCorr helper.
Refs #7468
Port CreateMDWorkspace GUI to new Python API. Refs #7468
Port reset of IndirectDiffractionReduction to new API.

Refs #7468
Port MDWDiag to new Python API. Refs #7468
Remove mantidsimple reference in comment. Refs #7468
Remove old API usage from SliceViewer tests. Refs #7468
Merge branch 'feature/7468_clearup_old_api_interfaces' into develop