Revise comments that are copied from cpplint.py

[matyalatte]

cpplint-cpp copied numerous comments directly from cpplint.py without modifications. Some of them do not match the implementation of cpplint-cpp.

For example, line_utils.h has python style docstrings and their return values do not match the actual APIs.

/*Find the position just after the end of current parenthesized expression.

Args:
    line: a CleansedLines line.
    startpos: start searching at this position.
    stack: nesting stack at startpos.

Returns:
    On finding matching end: (index just after matching end, None)
*/
void FindEndOfExpressionInLine(const std::string& line,
                               size_t* startpos,
                               std::stack<char>* stack);