syntax_tools: Fix an erroneous type and strengthen some specs

[Kostis Sagonas]

The declaration of the stubDescriptop() type in 'igor' was erroneous,
both in the -type and in the published documentation of the module.

While fixing this some specs where strengthened and used a remote
type to refer to ordsets:ordset(T). Consequently, this patch depends
on the ordsets module exporting the ordset/1 type.


   git fetch git://github.com/kostis/otp.git syntax_tools-fixes


Kostis