add a lua filter for A&A acks

aa/demo-structured_abstract.md

@@ -38,3 +38,5 @@ See the aastex demonstration^[<https://github.com/privong/papers-in-markdown/tre
 
 G.C.P. acknowledges support from the University of Florida.
 This work makes us of the `pandoc` universal document convertor^[<https://pandoc.org/>].
+
+{{end_acknowledgments}}

aa/demo-traditional_abstract.md

@@ -33,3 +33,5 @@ See the aastex demonstration^[<https://github.com/privong/papers-in-markdown/tre
 
 G.C.P. acknowledges support from the University of Florida.
 This work makes us of the `pandoc` universal document convertor^[<https://pandoc.org/>].
+
+{{end_acknowledgments}}

aa/filters/acknowledgments.lua

@@ -0,0 +1,38 @@
+--[[
+Simple pandoc filter to handle the {{acknowledgments}} macro.
+
+Copyright (C) 2018 George C. Privon
+
+This program is free software: you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation, either version 3 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program.  If not, see <http://www.gnu.org/licenses/>.
+]]--
+
+return {
+  {
+    Str = function (elem)
+        if elem.text == "{{acknowledgments}}" then
+            if string.find(FORMAT, "latex") then
+                return pandoc.RawInline("tex", "\\begin{acknowledgements}")
+            elseif string.find(FORMAT, "html") then
+                return pandoc.RawInline("html", "<h1>Acknowledgements</h1>")
+            else
+                return elem
+            end
+        elseif elem.text == "{{end_acknowledgments}}" then
+            if string.find(FORMAT, "latex") then
+                return pandoc.RawInline("tex", "\\end{acknowledgements}")
+            end
+        end
+    end,
+  }
+}