SVG plugin additions

[micheus]

My modifications aren't complete but I will make a PR for wpc_svg_path.erl when it is ready.

Nice.
Just have in mind that this stuff can be a nightmare. It's hard to cover all options that came with different software exporting this format. Please have this in mind otherwise we have problems keeping the compatibility of kind of plugin.

These issues were related to a change made to Inkscape that may need to be checked:
- Inkscape .svg path import internal error
- SVG import more broken than before?


and just to illustrate and show you that it's hard to make it work with all exporters take a look at this thread in which the user tkbd helped with the PS/EPS exporter to minimize the issues when getting it from Illustrator, Inkscape and LibreOffice: When Import any ps/eps file,Output error log

So, please try to test your changes to other apps than Inkscape.