Add some common functions to BaseTemplate

Add some common functions to BaseTemplate

Breaks any skins with same-name functions with different
visibility/functionality. Should mostly only be anything
based on Example, because that had everything set to private
for some reason. Normal skin practice for most others is to
use totally different names anyway. (eg 'render...' instead
of 'get...', and visualClear output done directly)

* clear: returns a visualClear
* getFooter: calls getFooterIcons and getFooterLinks and
  handles all the output; format is common to nearly every
  skin since MonoBook
* getAfterPortlet: same as renderAfterPortlet, but doesn't
  directly print content
* getTrail: same as printTrail, but doesn't directly print
  content

Also made the existing print versions for the last two  use
the new getters.

Change-Id: I5621f585b501e47b40ae80e9cb12e6a32da72275