test runner: output fileName&lineNo for `new Error()` exception
test runner: output fileName&lineNo for `new Error()` exception

also: fixes a bug when a custom exception is thrown. In this case
we try to extract the message with toString() on the custom exception
ashwinrayaprolu1984/ringojs,Transcordia/ringojs,ashwinrayaprolu1984/ringojs,Transcordia/ringojs,ringo/ringojs,ashwinrayaprolu1984/ringojs,ashwinrayaprolu1984/ringojs,Transcordia/ringojs,Transcordia/ringojs,ringo/ringojs,ringo/ringojs,ringo/ringojs