- conv=sparse option requires knowledge of File/Stdout to change
behaviour.
- Unclear how best to impl this.
- Possible option: develop 4 versions of dd<X,Y> for each valid pair of { File, Stdin,
Stdout }.
- Moves all arg parsing & tests to parseargs.rs
- Moves conversion tables to conversion_tables.rs
- Adds ebcdic_lcase and _ucase tables
- Refactors options: This **Breaks Write for Output**
- Adds support for calling dd fn from cl
- Adds basic cl tests from project root
- Adds support for multiplier strings (c, w, b, kB, KB, KiB, ... EB, E,
EiB.