Fixes#4598.
#4474 made the JSON time conversion no longer invertible, which caused
problems for chat, which uses message timestamp in milliseconds as a key
-- so chat would send a message with ms timestamp x, it would get
encoded as @da x, but then when it went back through the conversion to
milliseconds, it would often (not always) get encoded as x-1.
I still do not fully understand why this is -- and why it doesn't seem
to be a problem with seconds based on cursory testing -- but integer
multiplication and division generally do not invert. And adding a half a
millisecond to the input date before converting it resolves the issue
and makes the functions invertible.
I added a regression test, so hopefully the next courageous adventurer
who winds up here after wondering why +unm looks funny will have a
safeguard against some of the mistakes I made.
State before: in chrono:userlib, there were second-resolution
@da-to-unix and unix-to-@da functions. In en/dejs:format, there were
millisecond-resolution @da-to-unix and unix-to-@da functions. The
@da-to-unix path in time:enjs confusingly rounded to the nearest
millisecond, meaning millisecond n was a label for [n-0.5, n+0.5) rather
than [n, n+1).
This adds a millisecond-resolution @da-to-unix and unix-to-@da to
chrono:userlib, and a second-resolution conversion to en/dejs:format.
It makes use of the chrono:userlib functions in en/dejs, and doesn't do
any rounding.
Backwards-incompatible changes:
- made unt:chrono:userlib take a @da rather than @.
Unflops the spur in +en-beam, +de-beam, and everything that calls either
of those, or works with the consequences of their output.
This includes clay's interface for mounting and unmounting, which now
no longer expects the arguments to contain an old-style spur.
