Beamer template: add logooption variable (#11456).

Closes #11452.

MANUAL.txt

@@ -2999,6 +2999,9 @@ These variables change the appearance of PDF slides using [`beamer`].
 `logo`
 :   logo image for slides
 
+`logooptions`
+:   options for logo image (e.g., `width`, `height`)
+
 `navigation`
 :   controls navigation symbols (default is `empty` for no navigation
     symbols; other valid values are `frame`, `vertical`, and `horizontal`)
@@ -3016,7 +3019,7 @@ These variables change the appearance of PDF slides using [`beamer`].
 :   image for title slide: can be a list
 
 `titlegraphicoptions`
-:   options for title slide image
+:   options for title slide image (e.g., `width`, `height`)
 
 `shorttitle`, `shortsubtitle`, `shortauthor`, `shortinstitute`, `shortdate`
 :   some beamer themes use short versions of the title, subtitle, author,

data/templates/default.beamer

@@ -125,7 +125,7 @@ $for(titlegraphic)$
 $endfor$}
 $endif$
 $if(logo)$
-\logo{\includegraphics{$logo$}}
+\logo{\includegraphics$if(logooptions)$[$for(logooptions)$$logooptions$$sep$, $endfor$]$endif${$logo$}}
 $endif$
 
 \begin{document}