daterange: support relative terms

Support relative terms when writing date ranges in the search and filter
commands with the -d flag. Syntax is inspired by the notmuch search
terms.

Terms can be written with spaces or underscores for a better
readability, so both "this_week" and "this week" are allowed. Terms are
not case-sensitive.

Some terms can be prefixed with either "this" or "last" where applicable
("this" is assumed by default if omitted):

- "today", "yesterday"
- ("this"|"last") "year", "month", "week"
- all weekdays (e.g. "Tuesday", "last_wed")
- all months  (e.g. "January", "last_feb")

Note that "month" should always be spelled out to prevent a possible
ambiguity with "Monday".

Weekdays and months do not need to be written out completely, i.e.
"February..March" and "Feb..Mar" are both understood.

Relative date terms can be used with the <N (year|month|week|day)>
syntax where N is a positive integer indicating the number of time units
in the past from today. The units can be abbreviated with a single
letter, e.g. "1w 1d.." is the same as "1 week 1 day..".

More examples:
:filter -d yesterday
:filter -d last_monday..
:filter -d mon..sat
:filter -d 1y1m1w1d..
:search -d this_week "PATCH aerc"

Signed-off-by: Koni Marti <koni.marti@gmail.com>
Acked-by: Robin Jarry <robin@jarry.cc>

0 files changed, 0 insertions, 0 deletions