ParametersI.h: Work around Ice bug in ParametersIPtr typedef
templates/combined.vm: Work around Ice bug in ${PojoI}Ptr typedef

I'm not happy with this patch.  The seemingly arbitrary escaping
of the leading '#' seems wrong, even if it does result in correct
generated output.  Is there a better way to do this?
OmeroCpp: Use IceInternal::Handle everywhere for Ice >= 3.4

This replaces the use of IceUtil::Handle, which will continue
to be used for Ice 3.3 and earlier.
OmeroCpp: Correctly forward declare wrapped types and upCast

IceInternal::Handle requires that the wrapped type be declared but
not defined.  This is a bit odd, but this is Ice.
IceInternal::Handle requires that upCast be explicitly defined for
every single type.  Templates are too hard, apparently!
OmeroCpp: Use correct typecasts
templates/combined.vm: Correctly forward declare wrapped types and upCast
Check row/column are not > han the size of table (See #9430)
Remove commented out code.
Add check if handle has not been created yet (see #9702)
Fix possible NPE if one date is null (see #9703)
Return the default is no group set (See #9684).
Returns the default group if no group set (see #9721)
Notify cancellation.
Fix search by time if either start or end not set. (see #9703)
Fix cancellation of image download.
Fix cancellation of archived file download.
Review cancellation of save as and script.
Add pthread configuration similar to autoconf

The new OmeroCpp/PThread SConscript file is now available
for checking various pthread configurations similar to
autoconf.

The file is called once by SConstruct and then recursively
calls itself in order to test the various pthread flags.
This is mostly determined by some strange calling errors in
SCons, but should allow with a little more work a fairly
self-contained pthread tool.

Note: several sections are still commented out since they
are unlikely to be immediately important for OMERO.
Revert BaseThreadPtr

Apparently because BT is a IceUtil::Thread
and not some other base class, IceInternal
Handle is inappropriate.
Remove Fixture f from unit tests

Fixture now attempts a connection causing
all these tests to fail. It was previously
needed when using boost::unit_test but is
no longer needed for gtest.