Enhanced Access Control subsystem,
supported by a new Authentication, Authorization and Accounting (AAA) module
exposed to lua as kumo.aaa.
The Handlebars template dialect now runs with recursive lookup
for improved compatibility with other handlebars implementations.
msg:check_fix_conformance() can now detect and attempt to fix issues where
the charset is invalid for parts that use transfer-encoding, by applying
any charset detection options, falling back to UTF-8.