Fix assertions, descriptor pools & sets, descriptor updates
Fix assertions, descriptor pools & sets, descriptor updates

* Assertions now use the :VK_SUCCESS enum corectly.

* Creating descriptor pools and sets should now be correct.  You'll need
to specify layouts manually for now.

* Updating a descriptor set takes preexisting VkDescriptor{xxxx}Info
structs and updates the given descriptor set via introspection.

npomf/hephaestus