Nanosecond times in Python (#522)

* initital implementation

* datetime replaces with sls::Duration in Python C bindings

* using custom type caster

* fix for conversion to seconds

* added set_count in python

* common header for pybind11 includes

authored-by: Erik Frojdh <erik.frojdh@psi.ch>

python/scripts/basic.py

@@ -3,22 +3,20 @@
 import os
 import sys
 import numpy as np
-from pathlib import Path
-sys.path.append(os.path.join(os.getcwd(), 'bin'))
+# from pathlib import Path
+# sys.path.append(os.path.join(os.getcwd(), 'bin'))
 
 from slsdet import Detector, Mythen3, Eiger, Jungfrau, DetectorDacs, Dac, Ctb, Gotthard2, Moench
 from slsdet import dacIndex, readoutMode
 from slsdet.lookup import view, find
 import slsdet
 
-
+from slsdet import DurationWrapper
 
 
 d = Detector()
-e = Eiger()
-c = Ctb()
-g = Gotthard2()
-# j = Jungfrau()
-# m = Mythen3()
-m = Moench()
+t = DurationWrapper(1.0)
 
+d.setExptime(t)
+
+# d.setExptime(0.3)