GitLab

 - returnining different values in callout_params_library.cc
 - returned values are now described for getParameter
 - corrected index syntax comment in getParameter
 - added missing include
 - hooks_user.dox updated
 - hooks unit test moved, so it is now next to other hooks tests

1. Updated Kea guide to note that removing the hooks-libraries
   configuration element does not always have the expected effect.
2. Moved some documentation from the dhcp_parsers.cc file to the .h file.
3. Expanded checking of the contents of the hooks-libraries configuration
   element.

As some incompatible changes have already been made to the hooks
interface (removal of the setSkip method), it seems pointless to
support both old and new hoos-libraries syntax.  These modifications
remove support for the old syntax.

Modify the tests of the hooks-libraries syntax to allow testing
of both the old and the new syntax.

Changed some EXPECT_EQ tests to ASSERT_EQ in cases where the length
of a vector was checked and subsequently followed by checks that
accessed elements of the array.  This way, if the array is too short,
the test will cleanly exit rather than possibly segmentation fault.

These tests were updated while investigating the issue described in
the ticket.

The interface-config map will hold the "interfaces" list which used to
be a global parameter. The new configuration layout is incompatible with
a previous layout.

 - Moved MAC operations to a new CfgMACSource class
 - Moved macros to HWaddr class
 - Added several unit-tests for MAC sources
 - MAC extraction code moved to separate function in Dhcpv6Srv

Also added some more unit tests for csv-format parameter.

Also, changed internals of the OptionDataParser:
- option parameters are validated in distnict functions to make code more
readable
- option data values are optional