Base knife-edge scan analysis implementation

Hi @lleguy @mercadil,

This is an example of a base implementation, specifically the knife edge scan analysis from Laurent's tb.knife_edge. This is agnostic from xarray data format, thus this can be easily used on other means, such as on a Karabo device.

I also have found out that there could be problems with using bisect especially with repetitive elements. I use slicing instead to find the valid range.

doc/getting_started.rst

@@ -15,10 +15,10 @@ If the toolbox has been installed in your home directory previously, everything
 
 .. code:: bash
 
-    pip install --user .
+    pip install --user ".[maxwell]"
 
 Alternatively, use the -e flag for installation to install the package in development mode.
 
 .. code:: bash
 
-    pip install --user -e .
+    pip install --user -e ".[maxwell]"