RFE: Better handling of .gitignore if it already exists on initial export

[jhgarrison]

trafficstars

On initial export into a directory that is detected to be a git repo, the export creates a .gitignore mentioning all the things that shouldn't be committed. However, if a .gitignore already exists, it is not updated with msaccess-vcs entries.

It would be nice if, in this case, there was a warning and the export wrote to an alternate filename, for example, msaccess-vcs.gitignore so the user could merge this with the existing file.