Catch exceptions by reference

We use polymorphic exception objects, so catching by value invokes
the copy constructor and stuff that we don't really want.
diff --git a/win/vncconfig/Connections.h b/win/vncconfig/Connections.h
index 3d3c06c..b3402ab 100644
--- a/win/vncconfig/Connections.h
+++ b/win/vncconfig/Connections.h
@@ -76,7 +76,7 @@
         try {
           network::TcpFilter::Pattern pat(network::TcpFilter::parsePattern(CStr(newPat.buf)));
           pattern.replaceBuf(TCharArray(network::TcpFilter::patternToStr(pat)).takeBuf());
-        } catch(rdr::Exception e) {
+        } catch(rdr::Exception& e) {
           MsgBox(NULL, TStr(e.str()), MB_ICONEXCLAMATION | MB_OK);
           return false;
         }
@@ -261,7 +261,7 @@
               (http_port != getItemInt(IDC_HTTP_PORT)) ||
               ((http_port!=0) != (isItemChecked(IDC_HTTP_ENABLE)!=0)) ||
               (rfb::Server::idleTimeout != getItemInt(IDC_IDLE_TIMEOUT));
-        } catch (rdr::Exception) {
+        } catch (rdr::Exception&) {
           return false;
         }
       }
diff --git a/win/vncconfig/Legacy.cxx b/win/vncconfig/Legacy.cxx
index 7d51de8..b56eb37 100644
--- a/win/vncconfig/Legacy.cxx
+++ b/win/vncconfig/Legacy.cxx
@@ -127,7 +127,7 @@
 
               // Finally, save the Hosts value
               regKey.setString(_T("Hosts"), TStr(newHosts.buf));
-            } catch (rdr::Exception) {
+            } catch (rdr::Exception&) {
               MsgBox(0, _T("Unable to convert AuthHosts setting to Hosts format."),
                      MB_ICONWARNING | MB_OK);
             }
@@ -148,7 +148,7 @@
           regKey.setBool(_T("AlwaysShared"), connectPriority == 1);
           regKey.setBool(_T("NeverShared"), connectPriority == 2);
 
-        } catch(rdr::Exception) {
+        } catch(rdr::Exception&) {
         }
 
         // Open the local, default-user settings