Some types of variable expansion do not work.

VNDS allows variables to be expanded within commands by prefixing them with a $ sign. For instance:

```
setvar str = "bg1.jpg"
bgload $str
```

will load the image "bg1.jpg". This appears to work in VNDS-LOVE. But there is a second type of variable expansion which uses brackets to delineate the scope of the variable name, allowing variables to be inserted into code without being surrounded by spaces. For instance:
```
setvar str = "bg1"
bgload {$str}.jpg
```
should load the image "bg1.jpg", just like the first example. However, this currently fails to work in VNDS-LOVE.