Update Object.ih. Add DigitalTopologyTraits. Improve speed of isSimple t...

Fix (hopefully) problem in homotopicThinning / isSimple.
Add DigitalTopologyTraits for that.
Improve speed by a factor 2.5.
![al-6-26](https://f.cloud.github.com/assets/793707/1439674/58544414-418e-11e3-919a-d0e55dcea591.png)
![cms-18-6](https://f.cloud.github.com/assets/793707/1439676/5e88f654-418e-11e3-8773-0b1a75fcc13f.png)
![dt-6-18](https://f.cloud.github.com/assets/793707/1439677/61c20c20-418e-11e3-9389-88b945321b64.png)
![cms-26-6](https://f.cloud.github.com/assets/793707/1439680/64eddeb0-418e-11e3-8b2d-aa3adc7bec63.png)
![bretzel-6-18](https://f.cloud.github.com/assets/793707/1439682/6a4abb8a-418e-11e3-950f-3fea9922dfa3.png)