SDRF editor prototype: introduced sdrf section enum
SDRF editor prototype: start using sdrf section enum instead of string constants
SDRF editor prototype: restricted the list of allowed sdrf column types per each sdrf section
SDRF editor prototype: added isFirst parameter to the sdrf section view as the view should be changed slightly for the very first section
SDRF editor prototype: sdrf columns dialog is quite functional now
SDRF editor prototype: implemented add/remove columns