[datafeed] add parser to import cubicweb xml
this parser is configurable through a mapping, which basically
tells which entity's relation should be copied. Multiple actions
to control backport of data are available:
* 'copy': copy the external entities locally (though marked as
coming from the data feed source)
* 'link': find similar entity internaly (e.g. for states)
* 'link-or-create': try to find a similar entity internaly, and create
it if necessary (won't be marked as coming from the data feed source,
e.g. for tags)
###############################################################################
#
# Put here information about external resources / styles used by your cube,
# or to overides existing UI properties.
#
# Existing properties are available through the `sheet` dictionary available
# in the global namespace. You also have access to a `data` function which
# will return proper url for resources in the 'data' directory.
#
# /!\ this file should not be imported /!\
###############################################################################
# CSS stylesheets to include in HTML headers
# uncomment the line below to use template specific stylesheet
# STYLESHEETS = sheet['STYLESHEETS'] + [data('cubes.%(cubename)s.css')]