Re #6494. Enable cancellation in case of erroneous input.

If the user inputs a log with a large range, print a warning and add
progress reporting and a couple of bonus spots where the algorithm can
be cancelled.
Re #6494. Handle variable deletion in a better way.
Merge remote-tracking branch 'origin/bugfix/6831_Indirect_C2E_createMapping_bug'
Merge remote-tracking branch 'origin/feature/7953_MultipleScatteringCylinderAbsorption'
Merge remote-tracking branch 'origin/feature/8011_clear_wininstallers_directory'
Merge remote-tracking branch 'origin/feature/7956_anvred_peak_corrections'
refs #7983. Implement python algorithm.

Python algorithm and tests created.
Merge remote-tracking branch 'origin/bugfix/8039_remove_pythonapi_refs'
Merge remote-tracking branch 'origin/feature/7895_spec_view_scrolling'
Merge remote-tracking branch 'origin/bugfix/8021_apply_corr_broken'
Correct the interpretation of DetectorDotDatFile

The Number of columns in a detector.dat file is 5 plus the number of user
table parameters. This commit correct this information.

re #8003
Correct the incorrect assumption of detectordotdat file

Although present almost always, according to the control group, the phi
column is the first of the User optional column. So, we can not suppose
it is there.

re #8003
Merge remote-tracking branch 'origin/feature/7756_muon_skt_times_gausdecay'

Conflicts:
	Code/Mantid/Framework/CurveFitting/CMakeLists.txt
Re #7756
Merge remote-tracking branch 'origin/feature/7824_seek_centre'
Merge remote-tracking branch 'origin/feature/8015_convfit_parameter_error'
Moved cleaning. Output seems to be much better. This refs #8045
Merge branch 'feature/8045_moving_cleaning_function' into develop