Fixed find_package(DART) on optimizer components

[mkoval]

Merging #630 uncovered some latent issues in DART's CMake configuration. The optional dart::optimizer components (bindings for nlopt, ipopt, and snopt) were not being added to the DARTTargets group and, thus, were not included in DARTTargets.cmake. This caused finding those components, e.g. via find_package(DART COMPONENTS nlopt), to fail even if they were built.

I thought the same issue would be present with FCLCollisionDetector and BulletCollisionDetector, but it appears that all of the available collision detectors are being linked into dart.so. There is dead code in those CMakeLists.txt file that indicates this was not always the case.

I found this surprising because merging all of these into one library seems undesirable. Was this an intentional change?

[jslee02]

We intended to build DART as a single library just for simplicity at the moment. However, as we plan to build DART component wise, collision should follow the same convention of optimizer components.

What I'm not sure is if this should be done in DART 6.0 or KIDO 7.0.

Besides on collision, this PR looks good to merge.

[mxgrey]

I think we should break things out component-wise with DART 6.0.

I believe pretty strongly that the only difference between DART 6.0 and KIDO 7.0 should be naming, while everything about their build systems, APIs, and features should be identical (except obviously that any usage of "DART" would be replaced with "KIDO"). I think that would make for the smoothest possible transition for users and developers alike.

[mkoval]

I am fine with putting off the other component changes to a future version.

However, I would still like to merge this PR. It is currently impossible for me to use find_package(DART COMPONENTS dart-optimizer-nlopt) in my code that depends on DART. This worked in the previous version, so it is a clear regression.

[jslee02]

I believe pretty strongly that the only difference between DART 6.0 and KIDO 7.0 should be naming, while everything about their build systems, APIs, and features should be identical (except obviously that any usage of "DART" would be replaced with "KIDO"). I think that would make for the smoothest possible transition for users and developers alike.

I like this plan. We can do this in separate pull requests.

👍 to merge this.