V1.1.0 EMF support added

Finally managed to add EMF support without too complex dependencies or multiple back and forth conversions (thus package number bump to 1.1).

Using Inkscape as basis which exists on Linux, Windows and Mac.

The conversion is implemented on the API side, not server side. Additional cleanup to the decimerapi was performed at the same time.

Imagemagick was alternative 1, but required additional dependencies and didn't work in the end anyway.
Also would have been different for Windows.
Pyemf is outdated, and even forks and can't do the targeted conversion.
There is also libreoffice possibility, but again, would have been different on Win vs Linux/Mac (and I think it can only convert to svg or pdf and thus requires further conversions).

What is the option to all this? Do a server side conversion, then user don't have to consider any system wide additional install. This might be a future fix. On the other hand, if a user wants to keep the converted EMF file (now as PNG) for further use, then the server function would have to be rewritten to return the new file. Thus current solution seems easiest.