add LuaTeX support and use it as the default engine

beamerfontthemejku.sty

@@ -26,7 +26,14 @@
 \RequirePackage{etoolbox}
 \RequirePackage{graphicx}
 \RequirePackage{xcolor}
-\RequirePackage{ifxetex}
+\RequirePackage{iftex}
+% legacy packages prior to merge into iftex; still relevant?
+\@ifundefined{ifluatex}{%
+    \RequirePackage{ifluatex}
+}{}
+\@ifundefined{ifxetex}{%
+    \RequirePackage{ifxetex}
+}{}
 \RequirePackage{listings}
 \RequirePackage{verbatim}
 
@@ -97,29 +104,29 @@
 
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 %% 
-%% Fancy fonts with XeTeX
+%% Fancy fonts with LuaTeX/XeTeX
 %% 
 
 \RequirePackage{lmodern}
 \RequirePackage{inconsolata}
 \RequirePackage{helvet}
-\ifxetex\else%
+\ifluatex\else\ifxetex\else%
     \RequirePackage{euler}
-\fi
+\fi\fi
 \RequirePackage{fontawesome5}
-\ifxetex\else%
+\ifluatex\else\ifxetex\else%
     % fix potentially mis-packaged FA5 in TeX Live 2017, see https://tex.stackexchange.com/q/497792/290236
     \pdfmapfile{=fontawesome5.map}%
-\fi
+\fi\fi
 %\usefonttheme{serif}
 \usefonttheme{professionalfonts}
 
-\ifxetex\else%
+\ifluatex\else\ifxetex\else%
     \ifbool{jkubeamer@xetexfonts}{%
-        \PackageWarning{beamerfontthemejku}{True-type fonts are only supported on XeLaTeX. Please consider switching to XeLaTeX to get the full look and feel of this beamer template. Note that you can silence this warning with the `nofancyfonts' option.}%
+        \PackageWarning{beamerfontthemejku}{True-type fonts are only supported on LuaLaTeX/XeLaTeX. Please consider switching to LuaLaTeX (or XeLaTex) to get the full look and feel of this beamer template. Note that you can silence this warning with the `nofancyfonts' option.}%
     }{}%
     \boolfalse{jkubeamer@xetexfonts}%
-\fi
+\fi\fi
 
 \ifbool{jkubeamer@xetexfonts}{%
     \ifbool{jkubeamer@eulermath}{

main.tex

@@ -1,4 +1,4 @@
-% !TeX program = xelatex
+% !TeX program = lualatex
 % !TeX encoding = UTF-8
 % !TeX spellcheck = en_US
 % !BIB program = biber
@@ -7,9 +7,11 @@
 %% to compile your LaTeX source file. If your tool does not support these magic comments,
 %% you will need to make appropriate manual choices.
 %% 
-%% You can safely use "pdflatex" instead of "xelatex" if you prefer the pdfLaTeX toolchain.
+%% You can safely use "pdflatex" instead of "lualatex" if you prefer the pdfLaTeX toolchain.
 %% However, pdfLaTeX will not be able to deliver the professional font experience that you
-%% will get with XeLaTeX.
+%% will get with LuaLaTeX. You can also safely use "xelatex" instead of "lualatex" while
+%% preserving the professional font experience if you prefer the XeLaTeX toolchain (or if
+%% LuaLaTeX does not work for you for whatever reasons).
 %% 
 %% _Important_: These magic comments should be on the first lines of your source file.
 %% 
@@ -274,7 +276,7 @@ \section{Prerequisites}
 \item Download the latest version of the theme package from \url{https://github.com/michaelroland/jku-templates-presentation-latex}.
 \item Extract its contents (unzip) and move the files to a location on your computer where {\LaTeX} will find them. The most portable choice is the folder of your main presentation file.
 \item Use \texttt{main.tex} (the source of this presentation) as a starting point for building your own presentation. It contains detailed guides about the various package options.
-\item Use \texttt{xelatex} as the {\LaTeX} typesetting engine (because it includes enhanced font support). \texttt{pdflatex} is also supported but does not deliver the full theme experience.
+\item Use \texttt{lualatex} (or \texttt{xelatex}) as the {\LaTeX} typesetting engine (because it includes enhanced font support). \texttt{pdflatex} is also supported but does not deliver the full theme experience.
 \end{itemize}
 \end{frame}
 
@@ -292,24 +294,24 @@ \section{Prerequisites}
 \item \texttt{datetime2}
 \item \texttt{etoolbox}
 \item \texttt{fontawesome5}
-\item \texttt{fontspec} (only with XeTeX)
-\item \texttt{hyperref}
+\item \texttt{fontspec} (only with LuaLaTeX/XeTeX)
 \end{itemize}
 
 \column{0.4\textwidth}
 \begin{itemize}
+\item \texttt{hyperref}
 \item \texttt{iftex}
 \item \texttt{inconsolata}
 \item \texttt{listings}
 \item \texttt{lm}
 \item \texttt{pgf}
 \item \texttt{psnfss}
 \item \texttt{translations}
-\item \texttt{xkeyval}
 \end{itemize}
 
 \column{0.2\textwidth}
 \begin{itemize}
+\item \texttt{xkeyval}
 \item \texttt{xcolor}
 \end{itemize}
 \end{columns}