[macros] Use maths mode for range delimiters (#5164)

Ranges are mathematical notation and not valid syntax, so it is more
appropriate to typeset them as maths than as code.

Author: jensmaurer

source/macros.tex

@@ -476,7 +476,7 @@
 \newcommand{\defexposconceptnc}[1]{\ecname{#1}\indexconcept{\idxexposconcept{#1}|idxbfpage}\itcorr[-1]}  % macro length: 18
 
 %% Ranges
-\newcommand{\Range}[4]{\tcode{#1#3,\penalty2000{} #4#2}}
+\newcommand{\Range}[4]{\ensuremath{#1}\tcode{#3}\ensuremath{,}\,\penalty2000{}\tcode{#4}\ensuremath{#2}}
 \newcommand{\crange}[2]{\Range{[}{]}{#1}{#2}}
 \newcommand{\brange}[2]{\Range{(}{]}{#1}{#2}}
 \newcommand{\orange}[2]{\Range{(}{)}{#1}{#2}}