Add support for partially initialized EMF images and EMF images with wrong transformation applied (Wine-generated)

[maxirmx]

• add support for EMF images without an initial viewport setup
• add handling of EMF images with wrong transformation applied (Wine-generated)

cc: @ronaldtse

This is a contribution from Metanorma (GitHub), a product of Ribose (GitHub).

[ronaldtse]

@kakwa this is the cleaned up PR originally at #37 .

Additional cleanups have also been made here:

• Migrated usage of Travis to GitHub Actions. We didn't know whether this is welcome but in our case we did it since it was easier for us to develop the fixes in.
• Migrated usage of Coveralls to latest best practice. This secret is used in the GHA build flow.

There are few steps to perform after merging this PR:

1. To enable Coveralls from GitHub Actions, set a secret for COVERALLS_REPO_TOKEN to the Coveralls' token obtained at the Coveralls page (This is https://coveralls.io/github/metanorma/libemf2svg in our fork).
2. Update the README badges to reflect status of your upstream repository. We changed them for easier viewing at our fork.

[ronaldtse]

@kakwa is there anything else we can do to merge this PR? Thanks!

[Kreijstal]

Thank you so much for this fork!