Config file: Whitespace in ; and | separate lists are not ignored and cause unexpected behavior

[HereThereBeDragons]

Given e.g. the following parameter
CVMFS_HTTP_PROXY="http://p1.site.example.org:3128| http://p2.site.example.org:3128; http://p3.region.example.org:3128| http://p4.region.example.org:3128"

This will not be correctly parsed as the whitespaces around each URL are not trimmed. As such, any URL starting with a white space will fail when trying to resolve it - defacto it will be ignored.

(For concrete example see #3440)

There is no obvious mentioning in the documentation that this is the case.
Also I would argue that it would be nice to allow to ignore white spaces around | and ; . Using whitespaces increases human readability and would be expected behavior nowadays.