Report customisation for GENVASC

This was our first attempt at customising a CiviReport. We used the Case Detail report as the model.

Two major issues:

Firstly, the report needs to show the relationships of the case subject, specifically their GP surgery. This was acheived by having two entries in the $this->_columns array that use the same DAO, specifically the CRM_Contact_DAO_Contact DAO, one for the contact being reported on (the subject of the study enrollment) and one for the 'relation' in question, viz. the GP surgery.

Secondly, the report needs to include the practice 'C' code, which is custom data associated with the GP surgery contact. Simply using $_customGroupExtends to include custom data against Individuals, Cases, Organisations and Addresses doesn't work, because although they show up on the form, there is no way to specify that the search criteria shouldn't search for them against the subject of the case, but instead use the related GP surgery.