Vendor dependencies.

This directory is the target directory for installing vendor dependencies (i.e., third-party libraries from external "vendors").

The directory is structured as follows:

• deps/checksums: vendor dependency checksums.
• deps/test: vendor dependency installation tests.
• deps/tmp: location for storing dependency downloads.
• deps/build: location for stored dependency builds.

Neither the tmp nor build directory should be committed to the project repository.