This patch ultimatedly removes format strings from Genode's base API.
Users of the former base/snprintf.h and base/console.h headers may
use the free-standing 'format' library hosted in the ports repository.
Fixes#2064Fixes#3869
Avoid use of REP_DIR in *.mk files to simplify the use of these files as
templates for a board hosted in a separate repository.
Use REP_INC_DIR for searching headers, thereby considering headers
hosted in an external repository.
Issue #3168
Put the initialization of the cpu cores, setup of page-tables, enabling of
MMU and caches into a separate component that is only used to bootstrap
the kernel resp. core.
Ref #2092