allow keywords as values in enums (and tagged unions)

compiler/token/token.odin

@@ -114,6 +114,10 @@ Kind :: enum u8 {
 	Keyword_C_Longdouble,
 }
 
+is_keyword :: proc(kind: Kind) -> bool {
+	return kind >= .Keyword_Func && kind <= .Keyword_C_Longdouble
+}
+
 Token :: struct {
 	span:       source.Span,
 	symbol:     symbol.Id,
@@ -122,5 +126,6 @@ Token :: struct {
 }
 
 Stream :: struct {
-	items: [dynamic]Token,
+	items:   [dynamic]Token,
+	symbols: ^symbol.Table,
 }