Implement 4 new fetches:
- ms_ltime
- ms_utime
- us_ltime
- us_utime
Which are the same as ltime and utime but with milliseconds and
microseconds input.
The converters also suports the %N conversion specifier like in date(1).
Unfortunately since %N is not supported by strftime, the format string
is parsed twice, once manually to replace %N, and once by strftime.
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