Add jsonOnly option to merge command

[jo-chemla]

Following discussion thread #44

This option is meant to avoid copying resources (tileset.json and tile contents) when merging multiple input tilesets. Results in a tileset.json that references input tilesets where they are stored.

Can add another commit to remove the --jsonOnly flag from the merge command to instead create a new command, mergeJson

[javagl]

Thanks. I tried it out locally, and ran the tests, and verified that the CLA was signed, and everything seems to be fine....

...except for that line endings thing. Quickly looking at the documentation, it seems like --end-of-line lf is the default, so that should not be given explicitly. If this is removed, I can merge this PR.

There's still the question about the line endings, though: I'll have to check what the best practices/policies are here. This should be unrelated to this PR, and may be handled in a small cleanup PR later.

[jo-chemla]

Woops sorry for pushing that change in package.json. Indeed this was just testing on my side, I reverted to the original package.json prettier command.

Edit: Note I also tried enforcing line endings to LF in .gitattributes at the root directry of the repo, it might be a good option to have it in the repo for future external windows-based contributors (eol can also be set to auto).

# .gitattributes
# Auto detect text files and perform LF normalization
* text eol=lf

[javagl]

Yes, it seems like using a .gitattributes is the way to go here. The desired behavior can also be configured by each user locally, but for the case that a user did not do this, the .gitattributes should take care of it. I'll confirm this internally, and likely create a PR to add this soon.

Thanks again for the mergeJson functionality.

(I'm usually updating things like the CHANGES.md and README.md prior to a release. So I'll probably schedule a release soon, and then also update these files accordingly)

[jo-chemla]

Thanks for helping me design that PR, and happy that I could help!