Make fake fire use the firelike drawtype

Not sure what you think to this, but I've modified fake fire so that fire uses the firelike drawtype, rather than plantlike...

Before:
![screenshot_812067125](https://cloud.githubusercontent.com/assets/4390945/5363580/1baecf8a-7fd5-11e4-8e92-5b771c518385.png)
After:
![screenshot_812022731](https://cloud.githubusercontent.com/assets/4390945/5363579/1ba95460-7fd5-11e4-9713-17339c86734f.png)

(Only merge if the server uses a MT build later than https://github.com/minetest/minetest/commit/9a685a4f2ec98f64c622f87690378b1c2a084473 which I presume it does.)