Merge remote-tracking branch 'origin/JEXL-367' into JEXL-367

# Conflicts:
#	src/main/java/org/apache/commons/jexl3/JexlArithmetic.java
#	src/main/java/org/apache/commons/jexl3/JexlFeatures.java
#	src/main/java/org/apache/commons/jexl3/internal/Interpreter.java
#	src/main/java/org/apache/commons/jexl3/parser/JexlParser.java
#	src/main/java/org/apache/commons/jexl3/parser/Parser.jjt
#	src/test/java/org/apache/commons/jexl3/jexl342/OptionalTest.java