The order should be (and now is):
1. magnum's own conversion constructors (double from integer and such)
2. stuff like implicit color3 -> color4, if applicable
3. buffer protocol constructors
4. general "init from a tuple" constructors last, because they're the
slowest
The clash of static constructors and members / properties is ...
unfortunate. This is resolved using a minor hack, but I think that's
warranted if it preserves C++/Python API compatibility. The
translation() static constructor and property is not done yet, tho.
Only the double ones, exposed as floats, because the extra ALU required
by doubles is negligible to function call overhead. It'll be different
for non-scalar types, but here I use this.