The installation directory of our python modules contains the major and minor
version number of python. For example, bii_scripts python modules are, on host
stretch and for python 3, installed at /opt/csr/lib/python3.5.

Now make determines the version number of the installed version of python2
and python3 and sets the variables BII_SCRIPTS_LIB_PYTHON and
BII_SCRIPTS_LIB_PYTHON3 accordingly.

If in a support module directory

  lib/pythonM.N/site-packages

exists, this is added to the PYTHONPATH variable.

This is needed since the command

  pip install  --prefix . .

installs python modules this way.

  
The hint on the license text was added to all bessyrules source files.
  
The original GPL v.3 was added as file LICENSE.

This allows to install *.id files into pki/own/private using
PKI_OWN += <ioc name>.id

This is to support generation of a pki file tree, see comments for usage.

We no longer treat iocBoot as a generated directory.

This was the case when BII_SCRIPTS_LIB was set.

These are now in a CONFIG file installed by the APPS_GENERICTEMPLATE module
which hosts the two tools.

As for other DL files, this also sets the vpath, so users don't need to do that.

It previously used RELEASE_DL_DIRS which means it only finds panel files in
support modules.

The python and python3 library directories can now ba set independently. This
is needed for some non-standard installations of bii_scripts.

A while back I changed the logic of disabling the MSI rules in base so that
the default is that they are disabled. You can define ALLOW_BASE_MSI_RULES
to override that default.

pg_request.py has the following advantages:
  * written in Python 3, not Python 2
  * uses psycopg2 instead of adodb, which is no longer maintained
  * the output formats "csv", "csv-quoted", "json" and "python" are
    created with standard python modules instead of beeing reimplemented
    in the script