Definitions/References popup

Using Dracula scheme (and Default theme) in Sublime Text I had blue links on dark background which were very difficult to read.

So I hack the Dracula.tmTheme by adding this (in settings section):

```xml
popupCss

#show-definitions {
background-color: #fff;
color: #282a36;
}
#show-definitions a {
color: #3b3a32;
}

```

May be it's not the better way to cope with this issue, but it works. May be can you fix it in your next official release?