Improve use of "non" vs. "non-"

[nspark]

• [X] Remove hyphen from non-{critical, existent, profit, standard, zero}
  • Rationale: All these are dictionary words without the hyphen.
• [X] Reword to avoid non-initializing
  • Rationale: Don't "solve" a problem you can avoid entirely.
• [ ] Fix "non-symmetric"
  • Plan: Reword use to avoid entirely

Closes #166

[jdinan]

Replaced by https://github.com/jdinan/specification/pull/17