IntPoint / double = IntPoint (should be Point)
Several things are wrong with `IntPoint`:
```c++
#include <iostream>
#include <2geom/int-point.h>
int main()
{
auto result = Geom::IntPoint{230, 231} / 2.3;
static_assert(std::is_same_v<decltype(result), Geom::Point>);
std::cout << result << std::endl;
}
```
This test program should compile and print `(100, 100.4347826086957)`. However,
* It doesn't compile, because `IntPoint` doesn't have an `operator<<`. As a workaround, we can include `<2geom/point.h>` to use `Point`'s.
* It doesn't compile, because the `static_assert` fails. Changing `Point` to `IntPoint` fixes the compile.
* It prints the wrong answer `(115, 115)`. This is because the `2.3` is getting converted to `2`, and then `IntPoint / int = IntPoint` is getting used.
issue