Version 1 of Walnut St Scenario: simplied CCTV facts.

Removed CCTV fact 'AtLocation(WalnutSt_People)', 'Membership(People_Pelts)' and 'NOT Membership(People_Pelts)'. Now only have 2 CCTV facts: 'AtLocation(WalnutSt_Pelts)' and 'NOT AtLocation(WaltnutSt_Pelts)'. This simplifies the overview diagram as there is one less level of inference. Previously 'AtLocation(WalnutSt_Pelts)' and 'NOT AtLocation(WaltnutSt_Pelts)' were inferred from the facts 'AtLocation(WalnutSt_People)', 'Membership(People_Pelts)' and 'NOT Membership(People_Pelts)'.