refactoring modules based on code review
refactoring based on code review
Merge remote-tracking branch 'origin/master'

Conflicts:
	modules/siddhi-core/src/main/java/org/wso2/siddhi/core/executor/expression/TypeExpressionExecutor.java
	modules/siddhi-core/src/main/java/org/wso2/siddhi/core/executor/function/ConvertFunctionExecutor.java
	modules/siddhi-core/src/main/java/org/wso2/siddhi/core/util/parser/ComparatorParser.java
Merge remote-tracking branch 'origin/master'

Conflicts:
	modules/siddhi-core/src/main/java/org/wso2/siddhi/core/event/converter/EventConverter.java
	modules/siddhi-core/src/main/java/org/wso2/siddhi/core/executor/function/attribute/FunctionAttribute.java
	modules/siddhi-core/src/main/java/org/wso2/siddhi/core/query/selector/QuerySelector.java