Adding test for timer attribute in int expr

src/main/java/avatartranslator/AvatarError.java

src/main/java/avatartranslator/AvatarSyntaxChecker.java

src/main/java/avatartranslator/AvatarTransition.java

...rc/test/java/avatartranslator/AvatarIBSStdParserTest.java

...ranslator/AvatarIntegerExprParsingAndEvaluationTests.java