Fix redundant (and slow): echo $(_lp_escape ...)

_lp_escape is: print "%q" "$*"
So echo $(_lp_escape ...) is a slow synonym for _lp_escape

Not all the usage cases are fixed in this commit. The remaining ones are
fixed in other patches with more global optimizations.
Merge pull request #182 from dolmen/fix/lp_escape-usage

Fix redundant (and slow): echo $(_lp_escape ...)