RRDtool dual process (remote creation/check) (#4104)

* Prepare for dual rrdtool processes
Disabled at this time
Split out rrdtool version checks into rrdtool_create_command()
Tests for rrdtool_create_command()
Fixes a few small issues.

* Enable dual process and remote rrd check/creation

* remove full path for remote commands

* Doc updates
minor fix to rrdtool_tune()

* Set up bootstrap for phpunit
Fix issues with FileExistsException

* Attempt to fix phpunit

* Fix classloader and bootstrap to use full paths only (not depending on $config)

* Fix phpunit tests, config.php does not exist.

poller.php

@@ -125,7 +125,7 @@ else {
     $influxdb = false;
 }
 
-rrdtool_pipe_open($rrd_process, $rrd_pipes);
+rrdtool_initialize();
 
 echo "Starting polling run:\n\n";
 $polled_devices = 0;
@@ -158,7 +158,7 @@ echo ("\n".'MySQL: Cell['.($db_stats['fetchcell'] + 0).'/'.round(($db_stats['fet
 echo "\n";
 
 logfile($string);
-rrdtool_pipe_close($rrd_process, $rrd_pipes);
+rrdtool_terminate();
 unset($config);
 // Remove this for testing
 // print_r(get_defined_vars());