[Context] Include fiber in printTo() output

emper/Context.cpp

@@ -100,7 +100,9 @@ void Context::printTo(std::ostream& strm, bool withPtr) const {
 	if (withPtr) {
 		strm << "(" << this << ") ";
 	}
-	strm << "[tos=" << tos;
+
+	strm << "[fiber=" << currentFiber
+       << ", tos=" << tos;
 	strm << ", bos=" << &context
 			 << ", saved-sp=" << savedStackpointer
 			 << ", *saved-sp=" << *static_cast<void**>(savedStackpointer);