This mainly serves two purposes:
(a) it saves a function call in ICore::instance()->foo() vs ICore::foo() at runtime
(b) it saves typing and reduces line noise when reading

It's also (mostly) source compatible, as ICore::instance()->foo() remains compilable.

Change-Id: Icf7be0bce17fefe3560473534a8991ff79cbecc3
Reviewed-by: Eike Ziller <eike.ziller@nokia.com>