Short constant names highlighted incorrectly

@vpetrovykh 已经在做这个了。

开始于 2018年7月20日。

Hi. 👋

Short constant names seem to be highlighted incorrectly. I got the assumption that the bug might lie in this MagicPython package. What do you guys think? I ran across this while coding a project, and thought that I should do something about it.

* **Editor name and version**: Visual Studio Code 1.23.1
* **Platform**: macOS 10.12.6
* **Color scheme**: Dracula
* **MagicPython version**: Default in Visual Studio Code 1.23.1

## VSCode Example

## GitHub Example

```python

LONGER = "Yeshh!"
B = "What?"

class SomeClass:
MEMBER = 1
MEMBER2 = 2
A = 3
ARE = 123
A85 = "Something"

```
I would also like to give special mention to short constant names that end in numbers. They don't seem to be highlighted correctly, even though the same length character-based constants do.