first pass schema for conditional declaration documents, closes #86
remove unnecessary macro.conditionContent
remove some obsolete files
data collection for conditionals data
collection.xconf for search
API module for conditionals, closes #87
Merge branch 'feature/conditional-api' into develop

New conditional API!
Merge branch 'feature/conditional-schema' into develop
Merge branch 'feature/remove-obsolete' into develop
bugfix: Makefile should not reference a removed target
first pass at tests
some schema bugfixes
schema change: allow tei:if to use model.conditionContent and tei:f to be in conditionals in declarations
bugfixes to conditionals API code
bugfixes and improvements to tests for conditionals API
Merge branch 'feature/conditional-tests' into develop

Closes #88
add validation to ensure uniqueness of conditional types
eXist r18233
Write wrapper functions for group membership/management information because in recent versions of eXist, basic group information is a secret.
use sm:list-groups() instead of sm:get-groups() which is deprecated