gnu: Add texlive-latex-tabto-ltx.

* gnu/packages/tex.scm (texlive-latex-tabto-ltx): New variable.

Signed-off-by: Ludovic Courtès <ludo@gnu.org>

gnu/packages/tex.scm

@@ -11609,3 +11609,41 @@ through the introduction of a new label which can be referenced like
 @code{\\pageref{LastPage}} to give a reference to the last page of a document.
 It is particularly useful in the page footer that says: Page N of M.")
     (license license:lppl1.3c+)))
+
+(define-public texlive-latex-tabto-ltx
+  (package
+    (name "texlive-latex-tabto-ltx")
+    (version (number->string %texlive-revision))
+    (source (origin
+              (method svn-fetch)
+              (uri (svn-reference (url (string-append
+                                        "svn://www.tug.org/texlive/tags/"
+                                        %texlive-tag "/Master/texmf-dist/"
+                                        "/tex/latex/tabto-ltx"))
+                                  (revision %texlive-revision)))
+              (file-name (string-append name "-" version "-checkout"))
+              (sha256
+               (base32
+                "1vq9s3n0mdgx2w84bjdsqxp3vcasfb824agjy56713902li1g8vm"))))
+    (build-system trivial-build-system)
+    (arguments
+     `(#:modules ((guix build utils))
+       #:builder (begin
+                   (use-modules (guix build utils))
+                   (let ((target (string-append (assoc-ref %outputs "out")
+                                  "/share/texmf-dist/tex/latex/tabto")))
+                     (mkdir-p target)
+                     (copy-recursively (assoc-ref %build-inputs "source")
+                                       target) #t))))
+    (home-page "https://ctan.org/pkg/tabto-ltx")
+    (synopsis "``Tab'' to a measured position in the line")
+    (description
+     "This package provides @code{\\tabto{<length>}}, which moves the
+typesetting position to @code{<length>} from the left margin of the paragraph.
+If the typesetting position is already further along, @code{\\tabto} starts a
+new line; the command @code{\\tabto*} will move position backwards if
+necessary, so that previous text may be overwritten.  In addition, the command
+@code{\\TabPositions} may be used to define a set of tabbing positions, after
+which the command @code{\\tab} advances typesetting position to the next
+defined ``tab stop''.")
+    (license license:lppl1.3+)))