Fix an issue reported by Szabolcs Horvát: the preamble control now allows return and tab key presses as input.
diff --git a/PowerPointLaTeX/PowerPointLaTeX/Preferences.Designer.cs b/PowerPointLaTeX/PowerPointLaTeX/Preferences.Designer.cs
index b6aa7ff..9066a36 100644
--- a/PowerPointLaTeX/PowerPointLaTeX/Preferences.Designer.cs
+++ b/PowerPointLaTeX/PowerPointLaTeX/Preferences.Designer.cs
@@ -234,6 +234,8 @@
             // 

             // miktexPreambleBox

             // 

+            this.miktexPreambleBox.AcceptsReturn = true;

+            this.miktexPreambleBox.AcceptsTab = true;

             this.miktexPreambleBox.Location = new System.Drawing.Point(7, 37);

             this.miktexPreambleBox.Multiline = true;

             this.miktexPreambleBox.Name = "miktexPreambleBox";