cppcheck-1.60

new checks:
* dereference iterator and then checking it in condition: 'if (std::isalpha(*i) && i != str.end()) { }'
* calling pure virtual function from constructor/destructor
* assert() condition calls function with side effects

improved checking:
* improved struct member leaks checking
* improved handling of variable initialisation in 'reassignment of variable (first assignment is redundant)' check
* better 'Prefer prefix ++/-- operators' checking for iterators
* handle more complicated patterns in checkIncorrectStringCompare

Lots of false positives and bugs have been fixed.