Add extra token for assembly assignment

Adding an extra token for := prevents whitespace between : = being valid

liblangutil/Scanner.cpp

@@ -596,7 +596,12 @@ void Scanner::scanToken()
 				token = Token::Period;
 			break;
 		case ':':
-			token = selectToken(Token::Colon);
+			// : :=
+			advance();
+			if (m_char == '=')
+				token = selectToken(Token::AssemblyAssign);
+			else
+				token = Token::Colon;
 			break;
 		case ';':
 			token = selectToken(Token::Semicolon);

liblangutil/Token.h

@@ -140,6 +140,8 @@ namespace langutil
 	T(Dec, "--", 0)                                                    \
 	K(Delete, "delete", 0)                                             \
 	\
+	/* Inline Assembly Operators */                                    \
+	T(AssemblyAssign, ":=", 2)                                         \
 	/* Keywords */                                                     \
 	K(Anonymous, "anonymous", 0)                                       \
 	K(As, "as", 0)                                                     \