Update Stylus filter with include paths
Update Stylus filter with include paths

Since the Stylus filter works with stdin, the compiler doesn't know the
source directory, and thus can't resolve any imports. This adds the
source directory to the include path using the `--include` option, and
also adds the `STYLUS_EXTRA_PATHS` option to configure any extra
include paths.
0x1997/webassets,heynemann/webassets,wijerasa/webassets,heynemann/webassets,scorphus/webassets,aconrad/webassets,aconrad/webassets,florianjacob/webassets,john2x/webassets,florianjacob/webassets,glorpen/webassets,glorpen/webassets,glorpen/webassets,JDeuce/webassets,heynemann/webassets,JDeuce/webassets,john2x/webassets,scorphus/webassets,0x1997/webassets,aconrad/webassets,wijerasa/webassets