Use fully qualified name for builtins description

  The descriptions are in the comment before the definition, and
now follow the pattern used in the comments for the net.tcp and
net.udp descriptions.
Do not reset exception value on unhandled exception

  The "except_unhandled_exception" identifier ends up being printed
just as `unhandled "unknown" exception' what may be misleading, so,
this change just reverts to the, yet record, original, generic exception
that was not handled by the try block.
Make onew_exception use a proper offset in namespaces

  This just changes it to use the logic in onew_slot, that is, when
needing to create storage for a spill or pure (hidden) temporary inside
a namespace, use the root record for global variables, as namespaces,
at least currently, are not really modules, just a pure namespace,
that happens to use the storage of global variables of its variables.
Implement code generation for the renew operator

  The renew operator is only applicable to vector types, and can be
used to shrink or expand a vector.