Major changes for MTLN redesign

[lmdiazangulo]

• step2gmsh --> step2tulip.
  • Moved into tulip repo.
  • step2tulip takes a .step and a .json and generates a .msh and a .tulip.json which runs directly into tulip as input.
  • step2tulip format is being redefined, a single entry point following the .fdtd.json philosophy.
• Tulip takes input directly from step2tulip and outputs a file written following the same structure as .fdtd.json.