Add $wgCapitalLinks option; if set to false, titles won't be forced to

Add $wgCapitalLinks option; if set to false, titles won't be forced to
have an initial capital. This isn't recommended in general, as it will
make "[[Asteroid]]s are..." and "... like [[asteroid]]s." point to
different pages.

It is meant mainly for languages which use the latin alphabet but don't
capitalize at sentence start (mainly conlangs) or for special purposes
where this is needed. This can *break links* and should not be changed
on an existing wiki without careful attention.