GitLab

- cppcheck issues
- Unique index for prefix and prefix length.

- Added new table host_identifier_type
- Added foreign key on hosts table referencing
  host_identifier_type
- Indexes on hosts table are now unique

- Rename GET_HOST_HWADDR_DUID to GET_HOST_DHCPID
- Fixes and clarifications in doxygen documentation

The updated API exposes functions which retrieve hosts
by any identifier and identifier type, rather than DUID
or HW address.

Committing on my discretion and with no objections on jabber.

    Merges in branch 'trac4316'

src/bin/dhcp4/dhcp4_messages.mes
    - Replaced the word "debug" with "informational" where appropriate

src/bin/dhcp4/dhcp4_srv.cc
    - Changed several lease4_logger messages from DEBUG to INFO
    DHCP4_INIT_REBOOT
    DHCP4_LEASE_ADVERT
    DHCP4_LEASE_ALLOC
    DHCP4_RELEASE
    DHCP4_DECLINE_LEASE

src/bin/dhcp6/dhcp6_messages.mes
    - Replaced the word "debug" with "informational" where appropriate

    - Added two new messages:
    DHCP6_LEASE_RENEW
    DHCP6_PD_LEASE_RENEW

src/bin/dhcp6/dhcp6_srv.cc
    - Changed several lease6_logger messages from DEBUG to INFO
    DHCP6_LEASE_ADVERT
    DHCP6_LEASE_ALLOC
    DHCP6_PD_LEASE_ADVERT
    DHCP6_PD_LEASE_ALLOC
    DHCP6_RELEASE_NA
    DHCP6_RELEASE_PD
    DHCP6_DECLINE_LEASE

    - Dhcpv6Srv::extendIA_NA() - added new log for DHCP6_LEASE_RENEW
    - Dhcpv6Srv::extendIA_PD() - added new log for DHCP6_PD_LEASE_RENEW

- Replace rand() with random()
- Use i++ rather than ++i

Also updated tests for Lease6::toText function.

This change was okayed on jabber by Thomas. The issue
occurred when static linking was enabled on OSX.

Linking a static lib from statically linked lib causes
various issues and isn't generally considered a good
idea.