Feature request: Allow reference to previous expression evaluations in debug console

It's often generally useful to be able to refer to the results of an earlier expression when exploring the state of a program. This is related to #281, but different. And possibly possible to implement.

result.getBlob("details")
> JDBCBlobClient (id=108)
result.getBlob("details").toString()
> "org.hsqldb.jdbc.JDBCBlobClient@63611043" (id=111)
Utils.fromJson(result.getBlob("details").getBinaryStream())
> BuildRequest (id=119)

This could be changed to

result.getBlob("details")
> JDBCBlobClient ($id_108)
$id_108.toString()
> "org.hsqldb.jdbc.JDBCBlobClient@63611043" ($id_111)
Utils.fromJson($id_108.getBinaryStream())
> BuildRequest ($id_119)

This would allow exploring the results from calls where repeating the call would return different results, and would also allow use of APIs that require objects as parameters, for example,

new byte[10000]
> byte[10000] ($id_120)
result.getBlob("details").getBinaryStream().read($id_120, 0, 10000)
> 200
new String($id_120)
> "The string result is displayed here..."

Start at the debug console entry point and examine how expressions are evaluated and displayed. Define how previous results receive references such as $id_108 and how those references can be passed into later expressions; done means results can be reused without repeating calls, including as object or array arguments.