CamlJava version 0.5

• Compatibility with OCaml 5.0 and up (#3)
• For OCaml root registration, use the more efficient generational API
• Update Makefile.config to OpenJDK 17 for Linux/AMD64

CamlJava version 0.4

• Add NewGlobalRef registration for classes involved in callbacks (#2)
• Compatibility with OCaml 4.09 and up
• Export "exception Exception of obj" in jni.mli
• Update Makefile.config to OpenJDK 8 for Linux/AMD64
• Migration to Github
• Add Jni.set_string_auto_conv to control autoconversion of strings
• Add Jni.set_debug to help debug stray exceptions
• Ensure that callbacks are done from main Java thread
• Fix confusion between fields of types "float" and "double"