Oral-B toothbrush holder/stand (single piece)

I combined two great designs for the Oral-B toothbrush holder for the Oral-B 3757 charging station by @villekl and @kronr, which improves the following things over other designs/remixes I have found:

* Stems and base are now combined into one single, monolithic piece, so there are no gaps or glueing
* Raised stems above base plate level for being able to clean them easier
* Cleaner geometry than other remixes I have found (I used the original wall mount from villeki and edited geometry in B