function invocation not colored consistently

還沒有人認領這個 Issue。

```py
bar = 1

def foo():
pass

foo()
bar += 1
```



Most theme's don't colorize `meta.function-call` as the idea is that it should cover function names, including the full path, and all parameters (see https://www.sublimetext.com/docs/3/scope_naming.html)

I good scope to give function names is `support.function`

先從 issue 中連結的 Python 語法突顯規則和 scope 命名指南開始，然後比較提供的範例和螢幕截圖。完成的標準是函式名稱取得所提議的一致 scope，同時不變更無關的突顯。

由索引模型根據 Issue 內容生成。