use 'const &' for Native_capability where possible

Native_capability are smart pointer and introduce some overhead when they
get copied for base-foc and base-nova. Reduce the performance penalty by
using const ref where possible.

Issue #905
nitlog: Fixed adaptation to changed nitpicker API

Fixes #955
Add 'Xml_node::has_sub_node' accessor
launchpad: Support configuration of launch entries

This patch enables the recursive startup of launchpad instances, which
was not possible since the recent removal of launchpad's built-in
default configuration.
hw: clearer naming scheme in kernel API

Rename kernel syscall in kernel call and the kernel-API
files in kernel/interface* .

ref #953
hw: use platform-thread pointer as pager badge

ref #953
hw: identify core threads through stack pointer

ref #953
hw: remove Kernel::get_thread

ref #953
hw: simplify Kernel::start_thread

Instead of writing initial thread context to the platform-thread members
and then communicating this core object to kernel, core calls
Kernel::access_thread_regs first to initialize thread context and then
Kernel::start_thread without a platform-thread pointer. This way
the frontend as well as the backend of Kernel::start_thread loose
complexity and it is a first step to remove platform thread from the
vocabulary of the kernel.

ref #953
hw: simplify Kernel::new_thread

Don't set priority and label in platform thread and then communicate this
core object via Kernel::new_thread but communicate priority and label directly.
This way kernel doesn't need to know anymore what a platform thread is.

ref #953
hw: don't provide thread base via platform thread

ref #953
hw: spelling fix in kernel/thread.cc

ref #953
hw: rename delete_thread in kill_thread

ref #953
hw: adjust expected serial start-message in run

ref #953
hw: get rid of Kernel::current_thread_id

Every thread receives a startup message from its creator through the initial
state of its userland thread-context. The thread-startup code remembers the
kernel name of the new thread by reading this message before the userland
thread-context gets polluted. This way, Kernel::current_thread_id becomes
unnecessary.

fix #953
hw: save MMU registers for TrustZone VMM (ref #954)

When saving/resuming translation table base registers, and data fault register
a VMM is able to translate the VM's virtual addresses, and to analyse aborts
it has generated.
hw: add TrustZone support for i.MX53 (ref #954)
vmm: add i.MX53 platform as target (ref #954)
imx53: add missing break to input driver (fix #957)
hw: initialize sctrl register appropriately

Fixes #916