Extract assignments from expression

Extract assignments from expression

Assignments explicitly enclosed in parentheses are ignored.

* MISRA C:2004, 13.1 - Assignment operators shall not be used in expressions
  that yield a Boolean value
* MISRA C++:2008, 6-2-1 - Assignment operators shall not be used in
  sub-expressions
* MISRA C:2012, 13.4 - The result of an assignment operator should not be used
* MITRE, CWE-481 - Assigning instead of Comparing
* CERT, EXP45-C. - Do not perform assignments in selection statements
* CERT, EXP51-J. - Do not perform assignments in conditional expressions