Begin shift over to using pandoc, markdown and llnextgen for reference manual. Fix man page URL while at it.

configure

@@ -284,11 +284,11 @@ probe CFG_GCC              gcc
 probe CFG_LLVM_CONFIG      llvm-config
 probe CFG_VALGRIND         valgrind
 probe CFG_PERF             perf
-probe CFG_MAKEINFO         makeinfo
-probe CFG_TEXI2PDF         texi2pdf
-probe CFG_TEX              tex
 probe CFG_MAKENSIS         makensis
 probe CFG_NATURALDOCS      naturaldocs
+probe CFG_LLNEXTGEN        LLnextgen
+probe CFG_PANDOC           pandoc
+probe CFG_PDFLATEX         pdflatex
 
 if [ -z "$CFG_ENABLE_CLANG" -a -z "$CFG_GCC" ]
 then