Re-evaluate sub-module visibility

[mjhouse]

DEAF is currently exposing a lot of structs and internal types that don't need to be used by consumers of the lib. These should all be hidden except for the following (tentative) list of visible structs/types:

• deaf::headers should expose only:
  • FileHeader
  • ProgramHeader
  • SectionHeader
  • common::constants::*
• deaf::tables should expose only:
  • Symbol
  • SymbolInfo
  • Relocation
  • RelocationInfo
  • SymbolTable
  • RelocationTable
  • StringTable
  • common::constants::* (?)
  • common::table_trait::Table

[mjhouse]

Resolved in 8c026fcddaf3bd0052a5c4179bcf03e61718eb4e