SVG2 colours

One sees these in Krita's native SVG gradients, a few hits online.

<stop 
  offset="0" 
  stop-opacity="1" 
  stop-color="#000000 icc-color(sRGB-elle-V2-g10.icc, 0, 0, 0)"
  krita:stop-type="color-stop"/>

and our parse_colour() in svg-list-read.c chokes on that (sees the # , counts the characters, bigger than 7 so parse error). Full details here (which has an EBNF specification). Not suggesting using that colour-profile information, at least not now, but don't error parsing it.

Given the EBNF, may be worth using re2c for this (generates C so no runtime depends). An example which parses URLs (populates a struct from a string).