rtcds: read in environment before setting flags and change flag tests to explictly look for non-empty strings.

The entire block of code for initializing environment variables has been moved before the command line flag checks.
The USERLAND_FLAG and NO_KERNELSPACE_FLAG default values are determined by the environment, but the /etc/advligorts files need to be read in first.

Command line flags are cleared if empty string, or set if not empty.  This wasn't obvious originally since the test for flags was
just [[ $SOME_FLAG ]].

The tests have been changed to [[ -n $SOME_FLAG ]] or in the negative case [[ -z $SOME_FLAG ]].
This doesn't change the behavior but is less ambigous to the eye.

NDS - replacing a gds based reference counting system with a smart pointer.

See merge request cds/advligorts!194

mmap_ptrs aren't copied in the code, so make it non-copyable, change from shared_ptr to unique_ptr.

brought in the daqd raii.hh helpers to give a make_unique that is available at any C++ revision that supports unique_ptr.

Simplified the get and set methods.

Removed the size method as it isn't used.

Minor cleanup to facilitate some gds restructuring by removing an unneeded gds dependency in the nds binary.

This replaces a raw pointer + separate reference counter with a std::shared_ptr that holds the pointer + tracks its reference count.

Update rtcds with user-space model flags

See merge request cds/advligorts!150

Epics only models

See merge request cds/advligorts!167

rtcds: refactor epics-only tests.  get_model_unit now produces the right unit_name for a given model name

python3-rtcds: fe_generator: some clean up of options.py.  CDSRFM start now fixed.

See merge request cds/advligorts!192

Add explicit calls to rt_fe_cleanup() to early exits from rt_fe_init().

Closes #159

See merge request cds/advligorts!193

fe: add explicit calls to rt_fe_cleanup() to early exits from rt_fe_init().  Fixes some bugs related to partial loading of the module: crash on server shutdown that hangs up server.  Can't reload module without rebooting server.

- Removed previous ADC timeout code
- Modified to use PCIe net time only if synched to time master.
See issue tracker log for more details.

local_dc: get rid of wanted by in systemd unit file.  Start of local_dc now...

See merge request cds/advligorts!191

local_dc: get rid of wanted by in systemd unit file.  Start of local_dc now sequenced by a systemd generator.  Also, this will stop the default behavior of starting local_dc on systems that don't need it.

Front end systemd generator

See merge request cds/advligorts!188

python3-rtcds: for fe_generator, EPICS_ONLY_MODELS environment variable now handled orthagonally to IOP_MODEL and USER_MODEL, reflecting a change in the puppet scripts for the site.

generator main.py renamed to __main__.py, and generator start script changes invocation the more pythonic 'python -m rtcds.fe_generator'

systemd_generator: moved to src/python/cds_frontend.  Will make it into a more generic front end control library.

Adjusting the default priorities of local_dc rts-transport@ and rts-epics@

See merge request cds/advligorts!187

This is to protect these critical processes in the FE system to make sure they do not get starved for CPU if there are other processes monopolizing the processor.

made lsmod system searches whole word only

Closes #187

See merge request cds/advligorts!166

Update local_dc to allow reading the model list from a systab file.

See merge request cds/advligorts!182

Include the headers needed for isspace.  Fix logic while looking for spaces.

Adjust strtok call in local_dc to split on space and tab.