Stabilize search-path in V2 CLI

[vojtechkral]

This is followup from #981 - since I am now relying on search-path, It would be nice if it could become a stable option (in the V2 interface, I presume).

Related to this, since I am calling tectonic from another tool in an automated way, it would be great if my tool could tell what CLI interface a supplied tectonic binary supports.

[pkgw]

@vojtechkral I'm not sure if I understand the second part of your request — you want your tool to be able to probe the CLI interface provided by Tectonic? I think the most straightforward way to do that is going to be running tectonic --version and activating various features based on when they were added.

[vojtechkral]

@pkgw Ok, that could be done, yes

[pkgw]

As for the first part of this issue, since the search path is part of the build specification, in the V2 document model it should really go into the Tectonic.toml file rather than be given on the command line. The goal is that tectonic build should always do the right thing without needing any additional arguments.

The status of this feature is basically as I recently commented in #985 (comment) : the basic idea is there but someone needs to sit down and write the code to implement it. I'm afraid that my priorities have been on HTML support lately, so I haven't been able to make progress on it personally, but I am more than happy to help work with someone else to implement it.