Add metadata.
Format: use spaces in angle brackets.
Remove unnecessary sublibs.
Add test_headers.
Fix issues find through test_headers.
Fix OpenCL test (WIP: hard-coded paths).

TODO: remove hard-coded paths (use site-config.jam or user-config.jam).
TODO: copy (or hard link) cl directory into test directory to run tests properly.
Rename aux -> detail, private -> detail.
Fix OpenCL problems (using anonymous namespaces to prevent multiple definitions and violation of ODR).