hal/comps/lowpass: make gain a pin

used in the remote HAL UI demo
gladevcp/widgets: fix for HAL_ProgressBar
tests/build/header-sanity: skip generated C++ protobuf headers

those are named '*.h' but are actually C++ includes
docs/highlight: support protobuf highlighting
shmdrv api: be more resilient when opening the driver

sometimes udev can take a while to get its act together, so be patient
rtapi/bitops: add atomic add_and_fetch primitives
rtapi: spin out integer types into separate include file
rtapi: hexdump library function
rtapi/ringbuffer: introduce multframe ring buffer API

This matches the format and terminology of zeroMQ frames and messages.
Used to support uniform end-to-end messaging of zeroMQ message streams
to and from RT components.

(c) Pavel Shramove 2014, MIT license.
rtapi: introduce rtapi_next_handle()

This provides a unique integer ID for all sorts objects. This ID is needed
to distinguish objects in the remote case where it is ineffcient to use
strings. The id counter is updated with an atomic operation, and resides
in the global segment.

Replaces the current muted-protected next_module_id() method.
rtapi/shmem: improve error message
rtapi/support: set pid tag for logging early

this avoids the case where a log message is tagged with pid -1 in the
startup phase.
ulapi_autoload: reduce log noise
ulapi_main: printf warning correction for size type
rtapi/xenomai: improve error messages
rtapi/shmem: API change to retrieve shm segment size

An omission, but a consequential one.
rtapi/app: introduce procfs thread creation API

This enables rtapi_app to create RT threads for kernel threads flavors
without the need of the threads module, and more felxible.

rtapi_compat.c: fix default xenomai flavor selection logic

no point in choosing xenomai-kernel over xenomai-user
rtapi_app: revamp

load kernel modules as specified in rtapi.ini
default to IPC socket for commands

use MACHINEKIT_INI
rtapi: revamp Submakefile

build for all flavors now

all module loading / unloading now goes through rtapi_app regardless
of userland/kernel threads flavors
rtapi_msgd: revamp