Ported MuSRFit GUI to qt4. May need more debugging.

src/external/MuSRFitGUI/MuSRFit4.pl

@@ -0,0 +1,17 @@
+#!/usr/bin/perl
+
+use strict;
+use warnings;
+
+use QtCore4;
+use QtGui4;
+use MuSRFit4;
+
+sub main {
+    my $app = Qt::Application(\@ARGV);
+    my $musrfit = MuSRFit4();
+    $musrfit->show();
+    exit $app->exec();
+}
+
+main();