This free add-on seamlessly integrates the Instant Meshes automatic retopology tool in Blender.
here is simple addon that uses the commandline version of Instant Meshes to integrate it into Blender.
What it does: Exports your object, runs InstantMeshes with the specified settings, imports the result and sets UVs and Materials, hides the original Object.
Of course if you want to have the paint option of the original program you have to do it all manually. But I have a couple of cases now, where the default is enough.
Feel free to improve it. (e.g. match the parenting of the original object, make sure it runs on Linux/Mac)
Apparently someone else did something similar some time ago which I wasn't aware of: see Blender Artists topic here.
I didn't look at it yet, but maybe someone could merge the best features of both.