GitLab

Including:
* Updates to comments etc.
* Addition of Lease4::operator==() (and associated unit tests)

* Corrections of miscellaneous typos in comments
* Update database version to 1.0
* Handling of truncation while fetching data from the database

Also, included dhcpsrv in the list of directories searched by Doxygen.

Add ability to select IPv4 leases by address and Subnet ID.

Make the names of the columns consistent between the lease4 and
lease6 tables.

This constructore is for use by the MySQL code.  By passing buffer
addresses and lengths, the need for the creation of intermediate
std::vectors is avoided.

... in preparation for adding IPv4 tests

Also fix some issues from the review.