Guix: Replace texlive-union with regular TeXlive packages

We can do this now that Guix has a texlive hook.

.guix-packages/ambrevar/tex.scm

@@ -126,46 +126,3 @@
 ;; font, together with support files for TeX (LaTeX).")
     ;; TODO: Fix license.
     (license license:gpl3+)))
-
-(define-public texlive-medium
-  (package
-    (inherit
-     (texlive-union
-      (list
-       texlive-latex-oberdiek
-       texlive-generic-ifxetex
-       texlive-latex-wrapfig
-       texlive-fonts-amsfonts           ; For custom letter?
-       ;; texlive-dvips   ; For custom letter and marvosym?  Already in texlive-union?
-       ;; texlive-latex-amscls
-       texlive-latex-amsfonts
-       ;; texlive-latex-amsmath
-       ;; texlive-latex-amsrefs
-       texlive-latex-capt-of
-       texlive-latex-hyperref
-       texlive-latex-url
-       ;; For custom letter
-       texlive-fonts-ec
-       texlive-latex-geometry
-       texlive-latex-xcolor
-       ;; For custom letter
-       texlive-fonts-marvosym
-       texlive-latex-eukdate
-       texlive-latex-needspace
-       ;; TODO: Does needspace needs microtype?
-       texlive-latex-pgf
-       texlive-generic-ulem
-       ;; For asymptote
-       ;; TODO: Can asymptote be used without those?  If not, add to propagated-input?
-       texlive-latex-media9
-       texlive-latex-l3kernel
-       texlive-latex-l3packages
-       texlive-latex-ocgx2
-       ;; For atlas document
-       texlive-latex-enumitem
-       ;; For org-letter
-       texlive-latex-koma-script
-       texlive-latex-ms)))
-    (name "texlive-medium")
-    (description "This is a very limited subset of the TeX Live distribution.
-It includes little more than texlive-tiny.")))

.package-lists/guix-manifest.scm

@@ -190,6 +190,30 @@
     "subdl"
     "sxiv"
     "tcpdump"
+    "texlive-base"
+    "texlive-fonts-amsfonts"
+    "texlive-fonts-ec"
+    "texlive-fonts-marvosym"
+    "texlive-generic-ifxetex"
+    "texlive-generic-ulem"
+    "texlive-latex-amsfonts"
+    "texlive-latex-capt-of"
+    "texlive-latex-enumitem"
+    "texlive-latex-eukdate"
+    "texlive-latex-geometry"
+    "texlive-latex-hyperref"
+    "texlive-latex-koma-script"
+    "texlive-latex-l3kernel"
+    "texlive-latex-l3packages"
+    "texlive-latex-media9"
+    "texlive-latex-ms"
+    "texlive-latex-needspace"
+    "texlive-latex-oberdiek"
+    "texlive-latex-ocgx2"
+    "texlive-latex-pgf"
+    "texlive-latex-url"
+    "texlive-latex-wrapfig"
+    "texlive-latex-xcolor"
     "the-silver-searcher"
     "time"
     "torsocks"