Add reader directives registry

reader-directive.scm

@@ -0,0 +1,23 @@
+(directive "#!bwp")
+(purpose "broken-weak-pair object")
+(implementations chezscheme)
+
+(directive "#!eof")
+(purpose "end-of-file object")
+(implementations chezscheme chicken gambit)
+
+(directive "#!fold-case")
+(purpose "change to case insensitive identifiers")
+(rnrs r7rs)
+
+(directive "#!no-fold-case")
+(purpose "change to case sensitive identifiers")
+(rnrs r7rs)
+
+(directive "#!r6rs")
+(purpose "change to R6RS read syntax")
+(rnrs r6rs)
+
+(directive "#!r7rs")
+(purpose "change to R7RS read syntax")
+(implementations gauche)