gap: don't use deprecated LaTeX() and LaTeXObj()

These functions were removed in 4.13.

Author: tornaria

src/sage/groups/libgap_wrapper.pyx

@@ -602,14 +602,11 @@ cdef class ElementLibGAP(MultiplicativeGroupElement):
             sage: from sage.groups.libgap_group import GroupLibGAP
             sage: G = GroupLibGAP(libgap.FreeGroup('a', 'b'))
             sage: g = G.gen(0) * G.gen(1)
-            sage: g._latex_()
-            "ab%\n"
-        """
-        try:
-            return self.gap().LaTeX()
-        except ValueError:
-            from sage.misc.latex import latex
-            return latex(self._repr_())
+            sage: latex(g)
+            \text{\texttt{a*b}}
+        """
+        from sage.misc.latex import latex
+        return latex(self._repr_())
 
     cpdef _mul_(left, right):
         """

src/sage/interfaces/gap.py

@@ -1562,16 +1562,10 @@ def _latex_(self):
 
             sage: s = gap("[[1,2], [3/4, 5/6]]")
             sage: latex(s)
-            \left(\begin{array}{rr} 1&2\\ 3/4&\frac{5}{6}\\ \end{array}\right)
+            \left[\left[1, 2\right], \left[\frac{3}{4}, \frac{5}{6}\right]\right]
         """
-        P = self._check_valid()
-        try:
-            s = P.eval('LaTeXObj(%s)' % self.name())
-            s = s.replace('\\\\', '\\').replace('"', '')
-            s = s.replace('%\\n', ' ')
-            return s
-        except RuntimeError:
-            return str(self)
+        from sage.misc.latex import latex
+        return latex(self._sage_())
 
     @cached_method
     def _tab_completion(self):