number.rs: Allow Plus-sign before radix marker

src/parser/instruction/encoding/number.rs

@@ -16,7 +16,8 @@ impl Parsable for Number {
     fn parse<'text, T>(p: &Parser, stream: &mut T) -> Result<Self, Error>
     where T: TokenStream<'text> {
         use Type::*;
-        let negative = stream.expect(Minus).is_ok();
+        // The number is negative when it begins with a Minus, but Plus is also acceptable.
+        let negative = stream.expect_any_of([Minus, Plus]).map_or(false, |t| t.is_variant(Minus));
         let radix = match stream
             .expect_any_of([RadixMarkerHex, RadixMarkerDec, RadixMarkerOct, RadixMarkerBin])
             .ok()