Feature request: fugitive_gi opens "local" .gitignore

[ANaumann85]

Currently the map gi with a counter opens the top-most .gitignore. It would be nice if the mapping would choose the nearest file.

Example:

.git/
.gitignore
report/.gitignore
report/README.md
report/README.pdf

If I choose to ignore report/README.pdf, then fugitive_gI should add the line README.pdf to the file report/.gitignore.

For even deeper levels, I think the first ignore file should be choosen.

[tpope]

The idea I had was that 1gi would open the top-level, 2gi would go one level deep, etc. I just never got around to implementing it.