Core Java types in Gosu

Because Gosu is built on the JVM, many core Gosu classes are Java types. For example:

The class java.lang.String is the core text object class for Gosu code.
The basic collection types in Gosu reference the Java versions. For example:
```
java.util.ArrayList
print(list.get(0))
```

Java packages in scope

All types in the package java.lang and java.util are always in scope. Gosu code that uses types in those packages does not need fully qualified class names or explicit uses statements for those types.

For example, the following code is valid Gosu:

var f = new java.lang.Float(7.5)

The following simpler syntax produces more readable code:

var f = new Float(7.5)