Fixed a little whoopsie with the OpenFileDialog filter

- Changed "*.txt" to "*.c" so it filters C Source files instead of text files

Author: ClonkAndre

SimpleScoclScriptCompiler/Main.cs

@@ -105,7 +105,7 @@ private void browseSourceFileButton_Click(object sender, EventArgs e)
         {
             using (OpenFileDialog ofd = new OpenFileDialog())
             {
-                ofd.Filter = "c source files (*.c)|*.txt|All files (*.*)|*.*";
+                ofd.Filter = "c source files (*.c)|*.c|All files (*.*)|*.*";
 
                 if (ofd.ShowDialog() == DialogResult.OK)
                 {