gnu: Add texlive-tsemlines.

* gnu/packages/tex.scm (texlive-tsemlines): New variable.

gnu/packages/tex.scm

@@ -5580,6 +5580,25 @@ cobordisms between circles, such as those used in TQFT and other mathematical
 diagrams.")
     (license license:lppl1.3+)))
 
+(define-public texlive-tsemlines
+  (package
+    (name "texlive-tsemlines")
+    (version (number->string %texlive-revision))
+    (source (texlive-origin
+             name version
+             (list "tex/latex/tsemlines/")
+             (base32
+              "1c7sjdrgqbjw6f2s3185k5rlkig643pkkahjisx16h0akbbdm4k3")))
+    (build-system texlive-build-system)
+    (home-page "https://ctan.org/pkg/tsemlines")
+    (synopsis "Support for the ancient @code{\\emline} macro")
+    (description
+     "Occasional Documents appear, that use graphics generated by TeXcad from
+the EmTeX distribution.  These documents often use the @code{\\emline} macro,
+which produced lines at an arbitrary orientation.  The present package
+emulates the macro, using TikZ.")
+    (license license:public-domain)))
+
 (define-public texlive-amiri
   (package
     (name "texlive-amiri")