* sdlog2: move from STAT.MainState to COMM.MainState

This fixes a bug where vehicle_system_status and the commander internal
state were conflicting.

This will need adaptations in logging tools.

* sdlog2: don't bother changing STAT.MainState

For compatibility reasons, let's stick to the used log field (but still
fix the bug where the buffer (union) was overwrittern.

same issue as in posix code: 64bit values are not atomic in general.

in detail:
- in the write method: the following are not necessarily atomic operations:
 	_last_update = hrt_absolute_time();
 	_generation++;
- appears_updated() was called with a lock held in some cases, but not
  in ioctl
- use the SmartLock class, so that unlock() is not needed before every
  return call. Makes it less error prone

Makes it easier to see that no class members are accessed

This fixes a race condition: uORB::Manager::get_instance() is used in a
multi-thread context, but the singleton initialization was not thread-safe.
Further, this avoids having to check for nullptr every time the singleton
is accessed.

uORB::Manager::initialize() is called when uorb is started. No one else
accesses the singleton before that point, because it is only used in the
orb_* methods, and in muorb. Both require uorb to be started already when
they are used.

Battery charge estimation: Refactor the filtering strategy and move it to the backend, doing integration before and filtering the resulting charge estimate

The RPi build is based on the same DriverFramework base like the QURT
build, therefore it should use the same empty sensor init function.

Now 'uorb test' can be called multiple times.

This is necessary when using multiple instances of a topic. However it does
not free the underlying resources, as it is assumed they will be used again
at a later point.

* Qflight: add intersil sensor driver

* df_isl_wrapper: change driver lib name to isl

* posix-config: add df_isl_wrapper start command to eagle startup

* isl_wrapper: cleanup isl wrapper

* isl: remove unused option -R

* isl: change the driver name to isl29501

* DriverFramework: updated submodule again

This is to get the latest `make fix-style` changes.

* df_isl29501_wrapper: rename wrapper all the way