Support Java code-generation of trap statements

[peterwvj]

We need Java code-generation of trap statements in the AGCO project. Below are some test scenarios.

class Entry

operations

-- Result is 2  
public noExcRaised : () ==> nat
noExcRaised () ==
trap - with return 6 in
  return 2;

-- Result is 18
public excCaught : () ==> nat
excCaught () ==
trap a with return a + a in
  exit 9;

-- Result is mk_(9, true)  
public excCaughtTupRes : () ==> nat * bool
excCaughtTupRes () ==
trap mk_(b,n) with return mk_(n,b) in
  exit mk_(true, 9);

-- Produces error (exception not caught)
public excNotCaught : () ==> nat * bool
excNotCaught () ==
trap mk_('a', 9) with return mk_(5,false) in
  exit mk_(true, 9);

-- Produces error (exception not caught because 9 does not match 2) 
public excBindNotCaught : () ==> nat
excBindNotCaught () ==
trap s in set {2} with return s
in
  exit 9;

-- Result is 9 
public excBindCaught : () ==> nat
excBindCaught () ==
trap s in set {9} with return s
in
  exit 9;


end Entry