Tidy up title page code

- improves readability with conditional indenting.
- makes code more version-control-friendly by putting each formatting command on its own line.
- factors duplicated styles out of \if@noSmallCapitals.
- documents beamer bug(?) causing \insertauthor to never be empty.

beamerthemem.sty

@@ -63,55 +63,86 @@
 %{{{ --- Titlepage --------------------
 
 \def\maketitle{\ifbeamer@inframe\titlepage\else\frame[plain]{\titlepage}\fi}
-
 \def\titlepage{\usebeamertemplate{title page}}
+
 \setbeamertemplate{title page}
 {
   \begin{minipage}[b][\paperheight]{\textwidth}
     \vspace*{\@mtheme@voffset}
-    \ifx\inserttitlegraphic\@empty%
+
-    \else%
+    \ifx\inserttitlegraphic\@empty\else
-    {
+    {% \inserttitlegraphic is nonempty
       \vbox to 0pt
       {% display title graphic without changing the position of other elements
         \vspace*{2em}
         \usebeamercolor[fg]{titlegraphic}%
-        \inserttitlegraphic{}%
+        \inserttitlegraphic%
       }%
       \nointerlineskip%
-    }%
+    }
-    \fi%
+    \fi
-    \vfill
+
-    \ifx\inserttitle\@empty%
+    \vfill%
-    \else%
+
+    \ifx\inserttitle\@empty\else
+    {{% \inserttitle is nonempty
+      \raggedright%
+      \linespread{1.0}%
+      \usebeamerfont{title}%
+      \usebeamercolor[fg]{title}%
       \if@noSmallCapitals%
-    {\raggedright\linespread{1.0}\usebeamerfont{title}\usebeamercolor[fg]{title}\inserttitle\par}%
+        \inserttitle%
       \else%
-    {\raggedright\linespread{1.0}\usebeamerfont{title}\usebeamercolor[fg]{title}\scshape\MakeLowercase{\inserttitle}\par}%
+        \scshape\MakeLowercase{\inserttitle}%
       \fi%
       \vspace*{0.5em}
-    \fi%
+    }}
-    \ifx\insertsubtitle\@empty%
+    \fi
-    \else%
+
-    {\usebeamerfont{subtitle}\usebeamercolor[fg]{subtitle}\insertsubtitle\par}%
+    \ifx\insertsubtitle\@empty\else
-    \vspace*{0.5em}
+    {{% \insertsubtitle is nonempty
-    \fi%
+      \usebeamerfont{subtitle}%
-    \begin{tikzpicture}\draw[alerted text.fg] (0, 0) -- (\textwidth, 0);\end{tikzpicture}%
+      \usebeamercolor[fg]{subtitle}%
-    \vspace*{1em}
+      \insertsubtitle%
-    \ifx\insertauthor\@empty%
+      \vspace*{0.5em}%
-    \else%
+    }}
-    {\usebeamerfont{author}\usebeamercolor[fg]{author}\insertauthor\par}%
+    \fi
+
+    \begin{tikzpicture}
+      \draw[alerted text.fg] (0, 0) -- (\textwidth, 0);
+    \end{tikzpicture}%
+    \vspace*{1em}%
+
+    \ifx\insertauthor\@empty\else
+    {{% \insertauthor is always nonempty by beamer's definition, so this
+      % code is always inserted:
+      \usebeamerfont{author}%
+      \usebeamercolor[fg]{author}%
+      \insertauthor%
+      \par%
       \vspace*{0.25em}
-    \fi%
+    }}
-    \ifx\insertdate\@empty%
+    \fi
-    \else%
+
-    {\usebeamerfont{date}\usebeamercolor[fg]{date}\insertdate\par}%
+    \ifx\insertdate\@empty\else
-    \fi%
+    {{% \insertdate is nonempty
-    \ifx\insertinstitute\@empty%
+      \usebeamerfont{date}%
-    \else%
+      \usebeamercolor[fg]{date}%
+      \insertdate%
+      \par%
+    }}
+    \fi
+
+    \ifx\insertinstitute\@empty\else
+    {{% \insertinstitute is nonempty
       \vspace*{3mm}
-    {\usebeamerfont{institute}\usebeamercolor[fg]{institute}\insertinstitute\par}%
+      \usebeamerfont{institute}%
-    \fi%
+      \usebeamercolor[fg]{institute}%
+      \insertinstitute%
+      \par%
+    }}
+    \fi
+
     \vfill
     \vspace*{\@mtheme@voffset}
   \end{minipage}