example files inconsistent with README

[mairin]

From nomis in #LGM -

"I am slightly surprised that the "link1.svg" demo file contains "next=inlink" and the target is inkscape:label="inlink" (instead of "id" as apparently requested by the README"

[mairin]

all of my working magicmockup files rely on inkscape's inkscape:label property on the layer group objects. we tried using only 'id' on the layer group objects without the inkscape specific lable property and it doesnt work :(

[garrett]

We could try one and use the other as a fallback. I guess it matters how Inkscape tags IDs. Obviously, if Inkscape does it one way, and it's not the ideal way, we should support both Inkscape's and vanilla SVG. If Inkscape adds the IDs to both inkscape:label and 'id', then we'll support the standards way only.

In other words, supporting the standard is very good (and we should always try to do this), but in usage, we need to make sure it's always as easy as possible to magicify documents in Inkscape.