Cleanups to resolve clang warnings

[chipbarnaby]

Description

Compilation with clang in Visual Studio produces numerous warnings.

This PR contains miscellaneous "harmless" changes that satisfy both VC and clang.

Changes include

• More careful attention to const-ness (especially const char *)
• Addition of inner { } in multi-level array initialization
• Hiding unused function args
• Conversion of some SIs to ints
• Use of more rigorous casts (e.g. replace stuff like (char *)rc )
• Member initialization in order of definition
• Addition of MSGORHANDLE, eliminating need for many (const char *) casts in messaging function calls
• Eliminate unneeded (INT) and (char *) casts in printf-style arg lists
• Add { } in potentially ambiguous situations (e.g. if ( xxx) if (yyy)).
• Add parens in compound logical expressions that relied on operator precedence (a || b && c -> a || (b && c) )

No behavior changes. No results changes. No documentation changes.

The PR should be immediately mergeable without impact. Perhaps some conflicts due to parallel development.