[S32-str/numeric] Multiple fixes; fudge for niecza
[S32-str/numeric] Multiple fixes; fudge for niecza

Failure checking is robust to exceptions; signed radix number tests
corrected; a bigint test added.

zostay/roast,skids/roast,b2gills/roast,dankogai/roast,zostay/roast,niner/roast,dogbert17/roast,b2gills/roast,dankogai/roast,cygx/roast,zostay/roast,skids/roast,laben/roast,bitrauser/roast,dogbert17/roast,cygx/roast,bitrauser/roast,laben/roast,niner/roast,cygx/roast,laben/roast,niner/roast,skids/roast,b2gills/roast,dankogai/roast,perl6/roast