NotImplementedException.java, UnhandledException.java: ADDED

*.java:
Changed all the code to use these new variables.
Also used static imports for ASTHelper.*VISIT_SUBTREE.
Issue #59 New refactoring - add parentheses around conditional and when mixed with conditional or

Fixed this issue.
It is fixed for:
- "condition and" and "condition or"
- "bitwise and" and "bitwise or"
- "bitwise and" and "bitwise xor"
- "bitwise xor" and "bitwise or"

Reverse refactoring (removing parentheses) has been blocked for them.