When using overrides without specifying a footer, footer theme is set to default

[rmartine-ias]

When presenting a file with overrides set, the lack of a footer key is interpreted as an empty footer, which is parsed as the default footer, which overrides the theme's footer.

Reproduction:

1. presenterm examples/demo.md (see progress bar)
2. Edit header of demo.md to include:

   theme:
    override:
      default:

3. presenterm examples/demo.md (see 1/9 in footer)

[mfontanini]

Thanks for the report! This should be fixed now, but let me know otherwise.