Refactor to use more the StatementStack

[tchule]

Some flag should be moved into the current statement context instead of being treated as a global value.

$this->_inFuncCall
$this->_inControlStatement
$this->_inFunctionStatement
$this->_inInterface
$this->_justAfterFuncStmt
....

We should know if we are inside a function statement with the context.

[tchule]

	$this->_csLeftParenthesis = 0;
	$this->_fcLeftParenthesis = 0;