Add "Emission angle" in the particle object editor

[Bouh]

Description

There is no way to configure the Emission angle in object properties of a particle object.
The only way is to use the action.

Solution suggested

Add an input to configure "Emission angle" in the particle object.

[tristanbob]

The angle of a particle emitter can be set by dragging the rotation of the object in the scene editor, or by specifying the angle in the Properties inspector.

I am not sure if this should be added to the object properties or not. I am leaning towards "no", since all other object types use the same method to set "angle".

However.... while someone is working on particles... perhaps look at adding these other actions?
#2225