It is no longer necessary for outside users of package gpu to explicitly
initialize a specific driver. The Direct3D driver is already internal,
this moves the OpenGL driver internally as well. The rename to opengl is
to avoid the name clash with the low-level "gioui.org/internal/glimpl"
package that we're about to rename.
Signed-off-by: Elias Naur <mail@eliasnaur.com>
Elias Naur