Add space after branch icon

[MartyBeGood]

The leaf_selected icon does this and without it, only half of this double-width character gets highlighted when you select its line. It wastes a tiny bit of horizontal space (that wasn't used by the line selection highlight anyway), but it looks so much better with it.

With the space:

Without the space:

[SmiteshP]

This is very dependent on the font and terminal one is using. The current default settings look fine to me, but of course users can make changes while setup function if its looking misaligned to them.