ebnf: add empty package, and ebnf grammar copied from wikipedia

Signed-off-by: Alejandro Mery <amery@geeks.cl>

ebnf/ebnf.ebnf

@@ -0,0 +1,25 @@
+(* vim: set ft=ebnf: *)
+letter = "A" | "B" | "C" | "D" | "E" | "F" | "G"
+       | "H" | "I" | "J" | "K" | "L" | "M" | "N"
+       | "O" | "P" | "Q" | "R" | "S" | "T" | "U"
+       | "V" | "W" | "X" | "Y" | "Z" ;
+digit  = "0" | "1" | "2" | "3" | "4" | "5" | "6" | "7" | "8" | "9" ;
+symbol = "[" | "]" | "{" | "}" | "(" | ")" | "<" | ">"
+       | "'" | '"' | "=" | "|" | "." | "," | ";" ;
+character = letter | digit | symbol | "_" ;
+ 
+identifier = letter , { letter | digit | "_" } ;
+terminal = "'" , character , { character } , "'" 
+         | '"' , character , { character } , '"' ;
+ 
+lhs = identifier ;
+rhs = identifier
+    | terminal
+    | "[" , rhs , "]"
+    | "{" , rhs , "}"
+    | "(" , rhs , ")"
+    | rhs , "|" , rhs
+    | rhs , "," , rhs ;
+ 
+rule = lhs , "=" , rhs , ";" ;
+grammar = { rule } ;

ebnf/ebnf.go

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+package ebnf