Reserve implements keyword

Author: mhermier

src/vm/wren_compiler.c

@@ -96,6 +96,7 @@ typedef enum
   TOKEN_FOR,
   TOKEN_FOREIGN,
   TOKEN_IF,
+  TOKEN_IMPLEMENTS,
   TOKEN_IMPORT,
   TOKEN_AS,
   TOKEN_IN,
@@ -608,6 +609,7 @@ static Keyword keywords[] =
   {"for",       3, TOKEN_FOR},
   {"foreign",   7, TOKEN_FOREIGN},
   {"if",        2, TOKEN_IF},
+  {"implements", 10, TOKEN_IMPLEMENTS},
   {"import",    6, TOKEN_IMPORT},
   {"as",        2, TOKEN_AS},
   {"in",        2, TOKEN_IN},
@@ -2791,6 +2793,7 @@ GrammarRule rules[] =
   /* TOKEN_FOR           */ UNUSED,
   /* TOKEN_FOREIGN       */ UNUSED,
   /* TOKEN_IF            */ UNUSED,
+  /* TOKEN_IMPLEMENTS    */ UNUSED,
   /* TOKEN_IMPORT        */ UNUSED,
   /* TOKEN_AS            */ UNUSED,
   /* TOKEN_IN            */ UNUSED,