Revise Sending Schools so you can create districts and schools to accommodate school contacts that may need access to multiple schools from one district

What we currently call sending schools should be made into sending school districts. The current school code field will become the district of residence code (this is needed for most state reports anyway). We will then add the ability to define schools (high schools, middle schools, etc.) for each district. Contacts will then be tied to the district and can be assigned one or more schools. The current school code value would then be moved to the newly-created school’s settings. Student Applications and reports will then need to be modified to use the new data structure.