Abnormal color display in tmux.
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## Correct color display in tmux.

## I use [Termius](https://termius.com/) as my terminal. When I start spacevim in a normal terminal, it display normally. But when I start spacevim in tmux,  the color display is abnormal. And the icon always not displayed properly.

## Screenshots
Screen shot in normal terminal
![image](https://user-images.githubusercontent.com/25839309/106544636-dcb49080-6542-11eb-814e-4df9b98d3770.png)

Screen shot in tmux
![In Tmux](https://user-images.githubusercontent.com/25839309/106544554-b3940000-6542-11eb-9ea0-029341196c82.png)


