Enhancements to date/time functions:

(1) Add support for time-shift modifiers of the form (+|-)YYYY-MM-DD HH:MM:SS.SSS
(2) Add the timediff(A,B) SQL function that returns the time-shift modifier
sufficient to move B to A.

FossilOrigin-Name: 574bf370b0b9a72eb0468e0e121d4d6171fc533883b66d335f6794ef5ee1f051

diff --cc manifest
index f27eb08f56e17421df166353567ef48c939852a2,e8c32527560cb9f37ea0399a54e929d7090b311b..2c733001ed3e4a7e82ff79eb22124d26848162f7
--- 1/manifest
--- 2/manifest
+++ b/manifest
@@@ -1,5 -1,5 +1,5 @@@
- C Minor\stweak\sto\sthe\sOPFS\sasync\sproxy\sto\sattempt\sto\saccount\sfor\sa\sspurious\shigh-load\sconsole\serror\smessage\swhich\swas\sreported\svia\sthe\ssqlite-wasm\snpm\sproject.
- D 2023-05-30T14:10:28.641
 -C Simplifications\sto\sthe\snew\stimediff()\slogic.
 -D 2023-05-30T14:46:30.043
++C Enhancements\sto\sdate/time\sfunctions:\n(1)\sAdd\ssupport\sfor\stime-shift\smodifiers\sof\sthe\sform\s(+|-)YYYY-MM-DD\sHH:MM:SS.SSS\n(2)\sAdd\sthe\stimediff(A,B)\sSQL\sfunction\sthat\sreturns\sthe\stime-shift\smodifier\nsufficient\sto\smove\sB\sto\sA.
++D 2023-05-30T16:40:42.849
  F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
  F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
  F LICENSE.md df5091916dbb40e6e9686186587125e1b2ff51f022cc334e886c19a0e9982724
@@@ -2071,8 -2072,8 +2072,9 @@@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a9
  F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
  F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
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 -R 200e909133393bbb7ad7eb71a74582fc
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++R 255227b4547145c8dcfb80a734de5898
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+ U drh
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++Z b0a2fbca407b458dcbae70cd95c3b03c
  # Remove this line to create a well-formed Fossil manifest.

diff --cc manifest.uuid
index 9393709a8cf9b6b156aab68ad074b16cba72833c,888730ba203d3e95b39ab11506d1df1a9d7194c0..40438d1a00a3d02f0d06a1677ccdf7b352c1ac0f
--- 1/manifest.uuid
--- 2/manifest.uuid
+++ b/manifest.uuid
@@@ -1,1 -1,1 +1,1 @@@
- a61467d1fbb7a2804bfdc685a38e0b738747b9afd42c25a78a938b114a822f61
 -d6954259bd3f8475f3804fd02a1591d037efa9df54da45776863c024ff90e596
++574bf370b0b9a72eb0468e0e121d4d6171fc533883b66d335f6794ef5ee1f051