updates to dragonfly custom: selecting one path among multiple available to avoid intra-group congestion, enabling multiple connections within a router row, fixing lp-io radix bug

Updating dragonfly model to take into account multiple links connecting the chassis, updating config files and workload generator as well

Preparing beta version for new dragonfly model, modifications to routings, adding documentation for generating config files, adding libtools to support C++ code compilation

Adding first pass of dragonfly custom model: routings (adaptive, progressive adaptive, minimal, non-minimal) should be functional with DF traces, need to update for making optimistic mode functional

- Fat Tree readme now includes documentation for the custom- "pruned"
fat tree layout which is used to create the Summit network.

- Cleaned up handle_kickoff_event()
- UR traffic no longer generates messages with destination to self
- Added num_chunks config param (fixes segfault in hash chunk tracking)

- Cleaned up handle_kickoff_event()
- UR traffic no longer generates messages with destination to self
- Added num_chunks config param (fixes segfault in hash chunk tracking)

Merging Xu's multi-application workload with MPI Sim layer, enabling time-stepped series data output for the MPI traces (single and multiple applications), updating documentation