Restructure Third Party Software

[ax3l]

This pull request is related to #586 and reorganizes third party software (even if we are our own third party).

• import mallocMC
  • can be overwritten with an installed mallocMC if found by CMake
• import cuda_memtest
  • this is an independent tool, forked from sourceforge, and should be developed independently
• import cmake-modules
  • might be used/referenced by other projects such as pngwriter or mallocMC and gets very infrequent updates
• mpiInfo is not exported (yet) since it is too small to be relevant and might not be necessary for ever
• src/tools as in Move Tools/CMake/ThirdParty to Own Repo #586 is not part of this pull request and will not be included via git subtree again in the future (but only removed and published in a separate repo)

The history, authorship and commits of the individual directories have been preserved in the new repositories with rewritten sha's, but for PIConGPU to keep the statistics clean we squash the thirdParty updates to a single commit per update.

The import was done, e.g., for mallocMC with

GIT_AUTHOR_NAME="Third Party" GIT_AUTHOR_EMAIL="[email protected]" \
  git subtree add --squash --prefix=thirdParty/mallocMC \
      [email protected]:ComputationalRadiationPhysics/mallocMC.git master

since git submodules which is the clean alternative is a pain for users (git clone ... && git submodule init, not included in github tar downloads, mixed commits, ...).

The teams @ComputationalRadiationPhysics/picongpu-maintainers and @ComputationalRadiationPhysics/picongpu-developers have also access to cuda_memtest and cmake-modules where the same policies as for the picongpu repositories shall apply. mallocMC is maintained by @slizzered @psychocoderHPC and @ax3l and stays like that in a separate team.

add documentation: #726

• import / squash via fake-author (to not over-weight a maintainer)

[ax3l]

@psychocoderHPC you can already rebase #640 against this pull request