Add flags to enable/disable markdown extra footnotes

flags.c

@@ -28,6 +28,7 @@ static struct flagnames flagnames[] = {
     { MKD_NODIVQUOTE,     "!DIVQUOTE" },
     { MKD_NOALPHALIST,    "!ALPHALIST" },
     { MKD_NODLIST,        "!DLIST" },
+    { MKD_EXTRA_FOOTNOTE, "FOOTNOTE" },
 };
 #define NR(x)	(sizeof x/sizeof x[0])
 

generate.c

@@ -676,7 +676,7 @@ linkylinky(int image, MMIOT *f)
 		mmiotseek(f, implicit_mark);
 		goodlink = !(f->flags & MKD_1_COMPAT);
 
-		if ( (!image) && S(name) && T(name)[0] == '^' )
+		if ( (f->flags & MKD_EXTRA_FOOTNOTE) && (!image) && S(name) && T(name)[0] == '^' )
 		    extra_footnote = 1;
 	    }
 	    
@@ -1684,7 +1684,8 @@ mkd_document(Document *p, char **res)
     if ( p && p->compiled ) {
 	if ( ! p->html ) {
 	    htmlify(p->code, 0, 0, p->ctx);
-	    mkd_extra_footnotes(p->ctx);
+	    if ( p->ctx->flags & MKD_EXTRA_FOOTNOTE )
+		mkd_extra_footnotes(p->ctx);
 	    p->html = 1;
 	}
 

main.c

@@ -64,6 +64,8 @@ static struct {
     { "alphalist",     1, MKD_NOALPHALIST },
     { "definitionlist",1, MKD_NODLIST },
     { "1.0",           0, MKD_1_COMPAT },
+    { "footnotes",     0, MKD_EXTRA_FOOTNOTE },
+    { "footnote",      0, MKD_EXTRA_FOOTNOTE },
 } ;
 
 #define NR(x)	(sizeof x / sizeof x[0])

markdown.h

@@ -103,6 +103,7 @@ typedef struct mmiot {
 #define MKD_NODIVQUOTE	0x00040000
 #define MKD_NOALPHALIST	0x00080000
 #define MKD_NODLIST	0x00100000
+#define MKD_EXTRA_FOOTNOTE 0x00200000
 #define IS_LABEL	0x08000000
 #define USER_FLAGS	0x0FFFFFFF
 #define INPUT_MASK	(MKD_NOHEADER|MKD_TABSTOP)

mkdio.h.in

@@ -91,6 +91,7 @@ extern char markdown_version[];
 #define MKD_NODIVQUOTE	0x00040000	/* forbid >%class% blocks */
 #define MKD_NOALPHALIST	0x00080000	/* forbid alphabetic lists */
 #define MKD_NODLIST	0x00100000	/* forbid definition lists */
+#define MKD_EXTRA_FOOTNOTE 0x00200000	/* enable markdown extra-style footnotes */
 #define MKD_EMBED	MKD_NOLINKS|MKD_NOIMAGE|MKD_TAGTEXT
 
 /* special flags for mkd_in() and mkd_string()