Overlap mitigation

[JesseCoretta]

Between certain packages in this suite -- schema, syntax, dsa/ldapserver, dsa/message and dua -- there are several instances of overlapping types, methods and constants.

Cases observed thus far:

• Controls
• Attribute components (AttributeTypeAndValue, Attribute, PartialAttribute)
• Result codes, errors derived from standards recommendations
• Request types, such as AddRequest
• Search Filters
• Distinguished Names
• Syntaxes, such as Postal Address, Octet String, et al

This discussion will cover measures taken to mitigate these issues. Much of this could be relocated to common, but I'm still mulling options.