Whenever there are abstract modules in the netlist and the pass does not
declare that it supports them, call `hierarchy -auto-top` or `hierarchy`
(depending on whether there is a module marked `top`) to instantiate
them first. This makes several CLI workflows much more usable, including
one as basic as:
$ yosys file.v -o file.il
o Not all derived methods were marked 'override', but it is a great
feature of C++11 that we should make use of.
o While at it: touched header files got a -*- c++ -*- for emacs to
provide support for that language.
o use YS_OVERRIDE for all override keywords (though we should probably
use the plain keyword going forward now that C++11 is established)
