SpreadsheetUI : Add sections for organising large Spreadsheets
SpreadsheetUI : Add sections for organising large Spreadsheets

Improvements
------------

- Spreadsheet : Added sections for the logical grouping of columns in large spreadsheets.

GafferHQ/gaffer,andrewkaufman/gaffer,lucienfostier/gaffer,ImageEngine/gaffer,hradec/gaffer,lucienfostier/gaffer,johnhaddon/gaffer,hradec/gaffer,ImageEngine/gaffer,johnhaddon/gaffer,andrewkaufman/gaffer,appleseedhq/gaffer,lucienfostier/gaffer,GafferHQ/gaffer,GafferHQ/gaffer,johnhaddon/gaffer,boberfly/gaffer,hradec/gaffer,boberfly/gaffer,boberfly/gaffer,GafferHQ/gaffer,johnhaddon/gaffer,appleseedhq/gaffer,hradec/gaffer,appleseedhq/gaffer,GafferHQ/gaffer,appleseedhq/gaffer,andrewkaufman/gaffer,andrewkaufman/gaffer,ImageEngine/gaffer,ImageEngine/gaffer,andrewkaufman/gaffer,boberfly/gaffer,lucienfostier/gaffer,johnhaddon/gaffer,hradec/gaffer