add emptyset to latex symbols, and fix double bracket characters

Author: JeffBezanson

base/latex_symbols.jl

@@ -481,6 +481,7 @@ const latex_symbols = Dict(
     "\\exists" => "∃",
     "\\nexists" => "∄",
     "\\varnothing" => "∅",
+    "\\emptyset" => "∅",
     "\\nabla" => "∇",
     "\\in" => "∈",
     "\\notin" => "∉",
@@ -924,8 +925,10 @@ const latex_symbols = Dict(
     "\\Dashv" => "⫤",
     "\\interleave" => "⫴",
     "\\Elztdcol" => "⫶",
-    "\\openbracketleft" => "〚",
-    "\\openbracketright" => "〛",
+    "\\openbracketleft" => "⟦",
+    "\\llbracket" => "⟦",
+    "\\openbracketright" => "⟧",
+    "\\rrbracket" => "⟧",
     "\\overbrace" => "︷",
     "\\underbrace" => "︸",