[c/en] Wrapping fixes and some copy edits/small additions

[sjrct]

This does a few things with the c/en tutorial.

1. Fix the word wrapping. A lot of lines were longer than 80 characters. Some small copy edits here to prevent line breaks in strange places.
2. Added note about void in to signal empty parameter lists and add void to existing empty param functions
3. Note about not using braces for one-statement control blocks.
4. Note about using field initializers for structs
5. Note about #pragma once, and about static inline funcs in headers. Wasn't sure if this was too niche to be usefully included.
6. Small copy edits

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  • [x] Yes, I have double-checked quotes and field names!