Man page fixes (#1364)

- Highlighting for options (-x, --x) now doesn't strip the prefix (may be whitespace).
- Escape sequences are now cross-platform compatible (directly taken by groff/troff [man's renderer])
- Now we check for the section before displaying the man pages.
- On MacOS, there is HTTP(n) which is different from our HTTP(1). This used to conflict with it, and we showed the wrong page. Now we specifically ask foir HTTP(1).
- Errors that might happen (e.g non executable man command) is now suppressed. So in the worst case (if anything regarding man execution goes wrong), we'll always display the manual.
- Docs for man pages.
- HTTPie man pages.
- Epilog for the man pages (see also)
- Auto-generated comments.

Author: isidentical

docs/README.md

@@ -279,7 +279,7 @@ Synopsis:
 $ http [flags] [METHOD] URL [ITEM [ITEM]]
 ```
 
-See also `http --help`.
+See also `http --help` (and for systems where man pages are available, you can use `man http`).
 
 ### Examples