added support to be able to select bosonic as system_type
Making sure all stages where operators are presented as choices filter for system_type appropriately
Merge branch 'dev' of https://github.com/grujic/tnt into dev

* 'dev' of https://github.com/grujic/tnt:
  changed the use_for_modifier field to false for the majority of terms used to construct hamiltonians, as they're not relevant
  Adding rect and delta function to available spatial functions
  Adding S+ and S- operators
  think sarah been changing some CSS
  want to pull in new error-aware code
changed some typos in spatial function defs
Merge branch 'dev' of https://github.com/grujic/tnt into dev

* 'dev' of https://github.com/grujic/tnt:
  Fixing operators defs
  Fixing spatial_function_defs
  Adding bosonic operators