Moves DisabledClientMapperForMapping wrapper to new Local attribute.
Removes Factory#NewUnstructuredBuilder in favor of new Unstructured
builder attribute.
* Rename variables and functions to match Go convention.
For example, UsageError --> UsageErrorf.
* Remove redundant or unreachable code.
* Simplify some utility functions (no functionality changes).
* Fix hanging 'if { return } else { return }' constructs.
* Fix several incorrect printf verbs.