Java exception -> condition

Each java exception is mapped to a condition of type '(exn java
exception-class) and cleaned.

Add jni-test and misc-utils projects in java dir, misc-utils jar
should be added always to classpath and jni-test only for testing.
Update README.md
Improving modifiers signature handling

Supports not only #t/#f, modifier lists, ie: (public static) is working.
Improving memory managment

- class macro set finalizer for class pointer
- field getter calls prepare-local-jobject to set finalizer and tag the
  pointer
Merge pull request #3 from chicken-mobile/exceptions

Exceptions