Don't allow the NTP support and asynchronous name resolving to be
disabled. pthreads are now a hard requirement.
NTP is the primary task of chrony. This functionality doesn't seem to be
commonly disabled (allowing only refclocks and manual input).
This removes rarely (if ever) used code and simplifies testing.
GNU readline switched to GPLv3+ in version 6.0, which is incompatible
with the chrony's GPLv2 license.
Drop support for the readline library. Only editline is supported now.
Split and convert the manual into four AsciiDoc documents, a document
about installation and three documents in the manpage type for
chrony.conf, chronyd and chronyc. The minimal man pages that were
maintained separately from the manual are replaced by full man pages
generated from AsciiDoc. Info files will no longer be provided.
Some parts of the manual are rewritten, updated or trimmed. The
introduction chapter is partially merged with README. The chapter about
typical operating scenarios is included in the chrony.conf man page.
