[yt-dev] Issue #1075: Switch HaloCatalog main loop to loop over io chunks (yt_analysis/yt)

New issue 1075: Switch HaloCatalog main loop to loop over io chunks https://bitbucket.org/yt_analysis/yt/issues/1075/switch-halocatalog-main-loo... Britton Smith: The loop over all halos in the HaloCatalog currently requires all processors to have the entire list of halos. This should be changed such that process groups work only on a single io chunk. Currently, only one io chunk exists even when the halo catalog is saved to multiple files. This needs to be reverted to one chunk per file first.