add maude syntax

Makefile

@@ -33,6 +33,10 @@ EXECS = \
 
 CABAL_FLAGS ?= -O -v0
 
+SYNTAXDIR := syntax
+SYNTAXFLAGS = \
+  $(patsubst %,--syntax-definition=%,$(shell find $(SYNTAXDIR) -name '*.xml'))
+
 .PHONY: all
 all: build
 
@@ -59,6 +63,7 @@ define pandoc
     DIRNAME="$(basename $@)" \
     FILENAME="$@" \
     pandoc -s --toc --template $(TEMPLATEDIR)/$(1).html -o $@ $< \
+      $(SYNTAXFLAGS) \
       --filter $(LANGFILTER) --filter $(NICE_DATE) --mathjax
 endef