Spawn window in editor

I implemented new functionality in editor which allows to spray prefabs saved by "save node" option. This is very useful if somebody would like to create large number of objects (lets say grass, trees) on the surface.
There are some parameters which modify each object randomly like random rotation on each axis and random scale. Also there is option to orient the spawned nodes by surface normal which is enabled by default.
The tool can be also precise when you set spawning area to 0 and count to 1 which will create object exactly under mouse cursor.
New window can also spawn multiple objects randomly to make a better result. Lets say you are spawning 5 different types of trees so it look more natural. You can also pick the same object many times to increase probability of spawning that object.

The surface which we are spawning at can be determined by graphical objects or physics objects, you can switch between them by choosing picking type of objects CTRL+6.
Spawn window can be enabled in View tab.

![spawn](https://cloud.githubusercontent.com/assets/2963404/2591720/5b3599cc-ba6e-11e3-9037-79fadaff8392.png)
![spawn2](https://cloud.githubusercontent.com/assets/2963404/2591721/5b3a12c2-ba6e-11e3-9099-e2a48752cf87.png)