Add Gauss Hermite Quadrature Fields

[ffreyer]

closes #118

TODO:

• [x] prototype model with Gauß Hermite Quadrature fields
• [x] basic tests
• [x] introduce a Field type
• [x] add Gaussian quadrature field
• [x] (cleanup) drop unnecessary diagonal wrappers
• [x] (cleanup) remove todos and reminders
• [x] figure out typing between "missmatched" models and fields
  • one vs two flavors in field affecting size of hopping matrix, maybe MirroredMatrix (#153)
  • fix temp array types in field
• [x] optimized math between in propose_local etc for different matrix types (real, complex, blockdiagonal, ...)
• [x] (optimization) adjust GHQ field values to 1, 2, 3, 4 for easier/more direct handling
• [x] (cleanup) remove prototype model
• [x] add field to measurement kernel for dispatch (or figure out some other was to optimize them)
• [x] test all the miss-matched field model combinations
• [x] cleanup DQMC mandadtory & optional (merge?)
• [x] ED tests for fields
• [x] linalg tests for fields
• [x] merge Hubbard models
• [x] fix global updates for complex greens function (det(U) is not 1 here, though we could probably just ignore the total phase?)