[makeotf] PSNameNotSpecified.otf

[frankrolf]

When building an OTF from a UFO without PS name, a zero-kB file named PSNameNotSpecified.otf is created. This is unnecessary.
In addition to that, I think makeotf could try and create the PS name automatically (from UFO Family/Style Name) if it doesn’t exist.

[frankrolf]

I think the deeper problem here is that makeotf requires the postscriptFontName in a UFO be set. makeInstancesUFO no longer requires the ps font name (as per this commit), so perhaps it would be a good idea to remove that requirement from makeotf altogether.

[miguelsousa]

makeotf.py is too messy to try to squeeze in a fallback solution for when postscriptFontName is missing in a UFO. So in #451 I simply made makeotf behave the same way as when a Type 1 font without /FontName is used as input, which is it fails.

I'll definitely try to implement a fallback solution for the rewrite version.