[Ur] Force the inclusion of an url

[Sergey Mironov]

Hi. I've faced a problem while writing a program which (among other
things) serves a CSS which refers to some images. Look at the
following CSS sinpet:

@font-face {
  font-family: 'Glyphicons Halflings';

  src: url ('Glyphicons_halflings_regular_eot/blobpage');
  src: url ('Glyphicons_halflings_regular_eot/blobpage?#iefix')format('embedded-opentype'),
        url ('Glyphicons_halflings_regular_woff/blobpage')format('woff'),
        url ('Glyphicons_halflings_regular_ttf/blobpage')format('truetype'),
        url ('Glyphicons_halflings_regular_svg/blobpage#glyphicons_halflingsregular')format('svg');
}

All the url arguments point to the resources provided by my UrWeb
program: I've generated a set of Glyphicons_halflings_regular_*
modules, every module contains "blobpage" function. The problem is
that UrWeb optimizes off all my modules since they have no references
in the top-level module. Of cause, It is possible to write top-level
function which would redirect requests to lower modules, but that
would be a huge boilerplate to be written by hand. May we think how to
deal with it? Maybe special *urp directive?

Regards,
Sergey