Further exception cleanup

Further exception cleanup
Use a new checked exception type (TJException) when passing through
errors from the underlying C library. This gives the application a
choice of catching all exceptions or just those from TurboJPEG.

Throw IllegalArgumentException at the JNI level when arguments to the
JNI function are incorrect, and when one of the TurboJPEG "utility"
functions returns an error (because, per the C API specification, those
functions will only return an error if one of their arguments is out of
range.)

Remove "throws Exception" from the signature of any methods that no
longer pass through an error from the TurboJPEG C library.

Credit Viktor for the new code

Code formatting tweaks