This removes the toskip parameter, which was only used by the RISC OS
front end. The toskip param was used to skip 8 characters which did
not need to be escaped from the start of the URL. The RISC OS front
end now orders the steps of its URL construction to avoid the need
for this.
The avoids situations were we threw away the length, only for
the caller to have to strlen the returned string.
Note, there seems to be a case of the amiga front end writing
beyond end of allocation. Added a TODO for now.
