Made all STL usages explicit to be able automatically find all usages of
particular class or function.

On some platforms sin and cos are calculated in single precision resulting in
diversity of results.

replaced "const InputArray&" => "InputArray"; made InputArray and OutputArray references. added "None()" constant (no array()).

a big patch; use special proxy types (Input/OutputArray, Input/OutputArrayOfArrays) for passing in vectors, matrices etc.

decreased the lower canny threshold in HoughCircles, helps to detect some circles in low-contrast images (ticket #518)