Re #10805 Modify solid angle correction for tubes
Merge remote-tracking branch 'origin/feature/8980_backtobackGSAS_wikipage'
Merge remote-tracking branch 'origin/bugfix/10817_errorHardmaskPlus'
Merge pull request #109 from mantidproject/sans_solid_angle_update

Re #10805 Modify solid angle correction for tubes
Re #10823. Adding original version of the script.
Merge branch 'feature/10823_basis_311' into develop