UV3 Pear Support

Pear support for UV3 is based on the concept of a variant of main Java Feature Structure class, indicated by a bit in the _flags. The variant used for Pears (called trampoline), when there is a different JCas cover class for a type (due to the PEAR having a different classpath for loading these), the variant instance is constructed like a normal one except for the flag setting and for not having its own int/Object arrays for features; instead it shares those with the base feature structure instance.

We use similar mechanisms as in V2 to manage this. To locate the trampoline we use the same jcas hash map mechanism as in V2, and switch in and out various instances of those maps as pear boundaries are crossed (same as in V2).