Separate Transformation

[threeal]

To make the transformation process simpler, especially when we need to do rotation transform only. Instead of doing this:

Transform2 transform();
transform.set_rotation(90.0);

auto transformed_point = transform * point;

It's better to write that like this:

auto transformed_point = Rotation2(90.0) * point;

In case we need to do all the transformation, it could also be more simpler:

auto transformed_point = Translation2(-5.0, 0.0) * Rotation2(90.0) * point;

And the good news is that we could specify the order of transformation. That's why i suggest it's better to separate the transformation into each of it's components (e.g. Transform2 will be separated into Rotation2, Scale2 and Translation2).

[threeal]

Closed by #46.

In the end, transform point directly from it's member function is more convenient than using external transform object.

Rather than:

auto transformed_point = Translation2(-5.0, 0.0) * Rotation2(90.0) * point;

It's better to use:

auto transformed_point = point.rotate(90.0).translate({-5.0, 0.0});