function invocation not colored consistently

还没有人认领这个 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`

先从 issue 中链接的 Python 语法高亮规则和 scope 命名指南开始，然后对照提供的示例和屏幕截图进行比较。完成的标准是函数名获得所提议的一致 scope，同时不改变无关的高亮显示。

由索引模型根据 Issue 内容生成。