Change to TimeConstraint framework (2.3.dev0)
This merge has some pretty big changes (and some small ones):
- Moving version number to separate py file instead of init
- Adding scipy to reqs (for interpolator)
- Adding TimeConstraint, gen_turb, and gen_spat_grid to top-level import
- Removing all con_spat_df/con_turb_df and changing rows to columns when necessary (related to con_tc)
- Adding the interpolator function
- Adding TimeConstraint to core
- Adding data_profile, data_sig and data_spectrum
- Adding related documentation and tests for new functionalities
- Fixing/expanding tests and docs for old functionalities