Add spacing after frametitle

Without it, the content is offset vertically.

beamerthemem.sty

@@ -190,17 +190,18 @@
 
 %}}}
 %{{{ --- Frametitle -------------------
+
 \setbeamertemplate{frametitle}{%
 % \nointerlineskip
 \begin{beamercolorbox}[wd=\paperwidth,leftskip=0.3cm,rightskip=0.3cm,ht=2.5ex,dp=1.5ex]{frametitle}
   \usebeamerfont{frametitle}\MakeLowercase{\insertframetitle}%
 \end{beamercolorbox}%
-\vspace{-.5em}
 \if@useTitleProgressBar
   \begin{beamercolorbox}[wd=\paperwidth,ht=1pt,dp=0pt]{frametitle}
     \progressbar@titleprogressbar
   \end{beamercolorbox}
 \fi
+\vspace{3em}
 }
 %}}}
 %{{{ --- pgfplots ---------------------