internal timing of transient F-stat map function

See merge request GregAshton/PyFstat!16

- Adds chains to saved data
- Add catch for when corner plots error

transient search: user option tauMin

See merge request GregAshton/PyFstat!15

pyCUDA version of transient F-stat

See merge request GregAshton/PyFstat!13

- Add transient window type
- Rename arrays -> coord_arrays to solve caching check bug

 -previously check was done in _optional_import
  [called from init_transient_fstat_map_features()]
 -this was the right place only back when still importing autoinit
 -now do check at the time of make_default_context()

 -make some functions internal in tcw_fstat_map_funcs.py
 -clean up debug messages
 -clean up code formatting

Conflicts:
	pyfstat/core.py