Add pbox to template
Fix a test
Suppress apparently irrelevant error message that appears only in tests

[Delivers #70183740]
[#70183740]

* 70183740-ghostscript-error:
  Suppress apparently irrelevant error message that appears only in tests
Merge branch 'master' of https://github.com/softcover/softcover

Conflicts:
	spec/commands/generator_spec.rb
Restore EPUB/MOBI previews