Assertions to clarify precise merging behavior.

Also added some additional documentation providing environment specific file
overrides.

Major change, to get some of the naming cleaned up;
  confer.ConfigManager -> confer.Config
  confer.NewConfiguration -> confer.Config

A few potentially breaking changes to unpublicized but public packages:
  reader.Readfile -> reader.ReadFile
  reader.Readbytes -> reader.ReadBytes
  reader.ExportAs : removed, it was broken and I might think about how to support
    marshalling into structs, if at all.