[minor update of SandwichFeatures]
- exclude H for number_of_RK_in_sw
- default min_sheet_angle_by_four_term_cen_res (defined by 3 middle residues in each edge strand)= '25' since during repopulated de novo design of 3_1L9N, '27.2' of min_sheet_angle was observed for ideal-looking decoy
- added a destructor
- more int than Size to reduce Xcode warnings
- restored accidently deleted 'do not face' phrases where appropriate
[integration tests comment]
- should not change other than features and features_database_schema (if any)