Options.cxx: Improve error handling and help display.

algo/base/Options.cxx

@@ -77,14 +77,14 @@ Options::Options(int argc, char** argv)
     auto result = parser.run();
     po::store(result, vm);
   }
-  catch (const boost::wrapexcept<po::unknown_option>& e) {
+  catch (const std::exception& e) {
     std::cerr << "Error: " << e.what() << std::endl;
-    std::cerr << cmdline_options << std::endl;
+    std::cerr << "Use '-h' to display all valid options." << std::endl;
     std::exit(EXIT_FAILURE);
   }
 
-  if (vm.count("help")) {
-    std::cerr << cmdline_options << std::endl;
+  if (vm.count("help") > 0) {
+    std::cout << cmdline_options << std::endl;
     std::exit(EXIT_SUCCESS);
   }
 
@@ -93,7 +93,7 @@ Options::Options(int argc, char** argv)
   }
   catch (const po::required_option& e) {
     std::cerr << "Error: " << e.what() << std::endl;
-    std::cerr << cmdline_options << std::endl;
+    std::cerr << "Use '-h' to display all valid options." << std::endl;
     std::exit(EXIT_FAILURE);
   }
 }