Resolve integer narrowing and sign mismatch warnings.
Remove extraneous symbol.
Fix forcing to/from bool warnings.
Merge pull request #820 from evoskuil/master

Remove extraneous symbol causing VC/mingw break, fix warnings.
Add missing exports to zgossip functions.
Workaround for unresolved external error in VS test builds.
Merge pull request #821 from evoskuil/master

Fix and workaround unresolved externals in VS builds.