What did you think about an implicitConversionOp ?

[sighoya]

One point against `implicitConversionOp` is to which degree we 
work on copies after conversion.

What means actually conversion?
Did we create a whole new value not sharing any parts to its 
original value or is it more a mix of creation and sharing?
Example: create a new List and deep copy the elements out of the 
original list vs copy only the pointer of the elements out of the 
original list.

Because of this reason, I would favor for `implicitCoercionOp` 
and making `implicitConversionOp` explicit over `to!T` à la 
`into` in Rust.