more readable case-insensitive regexes

regex brackets are being used for case-insensitivity, e.g.,

```
[Ll][Ii][Pp][Ii][Dd][ |\\.|_]*[Cc][Ll][Aa][Ss][Ss]
```

I think this can be replaced with `(?i)` like this:

```
(?i)lipid[ |\\.|_]*class
```