7efc75c709
This commit introduces `EditMeshData`. The fields in this struct are extracted from `EditDerivedBMesh` into their own struct `EditMeshData`, which can then also be used by the `Mesh` struct. This allows passing deformed vertices efficiently to the draw routines. The modifier code constructs a new Mesh instead of writing to ob->data; even when ob->data is a CoW copy, it can still be used by different objects and thus shouldn't be modified by a modifier.