High level overview

New api version v20190401 in namespace ::cryptolens_io::v20190401
Api version v20180502, i.e. namespace ::cryptolens_io::v20180502, remains source code compatible with previous releases. The file src/base64.cpp was moved to third_party/base64_OpenBSD/base64.cpp, third party build scripts may need to be updated.

Api version v20190401

A summary of the changes from api version v20180502 to api version v20190401:

Instead of directly templating basic_Cryptolens with a RequestHandler and a SignatureVerifier it now takes a single template paramter Configuration. Several default Configuration classes are provided, see README.md for more details.
The API now automatically performs more basic sanity checks using the ActivateValidator from the choosen configuration class. In particular, Configuration_Unix and Configuration_Windows automatically compare the expires field on the license key to the systems local clock. If one does not want to perform this check, use Configuration_Windows_IgnoreExpires or Configuration_Unix_IgnoreExpires.
All constructors now take a basic_Error & argument, allowing us to report failures from the constructor.
Machine codes are now computed in the library by selecting a MachineCodeComputer policy class. The machine_code parameters have been removed from all methods. If one desires the old behaviour one can use the MachineCodeComputer_static policy class.
Added support for the Cryptolens Messaging API with the last_message() method.
Added support for creating trial keys with create_trial_key().
(Mostly internal) Interface of RequestHandlers was changed.