Introduce a new base module

[bal-e]

This introduces a new_base module as a potential candidate for replacing base. While it has a similar structure (although much is left to be filled out), it has three distinguishing features:

1. It builds the foundation for a derive-based interface for easily and efficiently parsing (and possibly building) DNS messages.

2. It introduces RevName, a more efficient type for domain names (where labels are stored in reverse order).

3. It relies on the zerocopy crate to offload basic byte parsing, and to represent big-endian integers where necessary. This saves a fair amount of parsing code.

There's a lot more work to be done. Procedural macros for deriving the various parsing traits need to be implemented. Basic record types (e.g. A) need to be defined. The OPT record is a special case that requires more attention. Common parsing targets (e.g. a standard IN-class query, and a fallback deconstructed message type) need to be defined. Parts of the existing codebase need to be adjusted to use new_base, to demonstrate its usefulness.