Update Nikon flash tags

[postscript-dev]

• Update Exif.NikonFl7.* tags
• Add Exif.NikonFl6 group (with help from ExifTool)
• Remove Exif groups list from the manpage instead of adding new NikonFl6 group
• Add NikonFl6 to Exif2 tag webpage documentation
• Update Exif.Nikon3.FlashMode with values from ExifTool

Closes #1941.

Ref: https://www.exiftool.org/TagNames/Nikon.html

[codecov[bot]]

Codecov Report

Merging #2274 (161565a) into main (e4adf38) will increase coverage by 0.14%. The diff coverage is 65.75%.

@@            Coverage Diff             @@
##             main    #2274      +/-   ##
==========================================
+ Coverage   63.16%   63.30%   +0.14%     
==========================================
  Files         119      119              
  Lines       20433    20620     +187     
  Branches    10164    10231      +67     
==========================================
+ Hits        12907    13054     +147     
- Misses       5403     5436      +33     
- Partials     2123     2130       +7     

Impacted Files	Coverage Δ
include/exiv2/tags.hpp	33.33% <ø> (ø)
src/makernote_int.cpp	64.62% <ø> (ø)
src/tags_int.cpp	77.67% <ø> (ø)
src/tiffimage_int.cpp	79.82% <ø> (ø)
src/nikonmn_int.cpp	61.46% <65.75%> (+4.32%)	:arrow_up:

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[postscript-dev]

@kevinbackhouse: When I was working on this PR, another change prevented automatic rebasing so I had to do this by hand. After finishing, when I pushed, git requested that I merge the code which I did. I see that a long list of commits have been included in this PR and I am unsure what to do. I was simply planning on squashing the commits when merging but I don't know if this will work. Do I need to do something else?

Also, I think that codeconv is failing due to the way in which merging took place. Exiv2 went through a period where the codeconv percentage produced weird values and I am wondering if merges like this have anything to do with it? This is only a suggestion though, as I don't have any experience with this.

[kevinbackhouse]

@postscript-dev: in this situation, I would create a temporary clone of the repo so that I can do potentially destructive things like git reset. If something goes wrong then I can just delete the clone and try again. I just gave it a try and I think these commands should work for you:

git clone https://github.com/Exiv2/exiv2.git exiv2_fix_pr_2274
cd exiv2_fix_pr_2274
git remote add postscript-dev [email protected]:postscript-dev/exiv2.git
git fetch postscript-dev 
git checkout Update_Nikon_flash_tags
git reset --soft main    # This is the dangerous command
git commit -m "Update Nikon flash tags"

At this point you should check that everything looks ok and that the tests pass.

Also, this command should return an empty diff, confirming that you didn't accidentally change anything:

git diff Update_Nikon_flash_tags postscript-dev/Update_Nikon_flash_tags

If everything looks ok, do a force push:

git push --force

[postscript-dev]

@kevinbackhouse:

I just gave it a try and I think these commands should work for you:

That worked great, thanks for the help.