One of the most glaring anomalies of the ClassFile API is the exposure of WritableAttribute without the reading counterparts. These writing hooks are almost never used by the clients, and their exposure imposes a massive maintenance burden and a blunt to understanding the best practices of the ClassFile API.

We must restrict the appearance of BufWriter to AttributeMapper only, just like its ClassReader counterpart; all other appearances and unrelated APIs will all be withdrawn to implementation.

Removals include:
- LocalVariable.writeTo
- LocalVariableType.writeTo
- WritableElement
- BufWriter.writeList/writeBytes/writeTo/copyTo
- ClassReader.compare