Do we really need ASCII-only text output?

[mpusz]

Besides the Unicode text output mp-units provides the ability to output ASCI-only text as well.

Standardizing such ASCII-only text output will be hard as ISO and SI standards do not specify alternative ASCII characters for those. This means we will have to guess and use some arbitrary things. Moreover, this complicates the design (e.g., requires an additional unit_symbol class template that stores two fixed_string objects).

Please let us know if you have issues with removing support for ASCII-only output and what is the rationale for keeping it.