Refactored optimization into LensTractor class, via driver method
Preparing to refactor initialisation of model. Spotted problem with contain_points...
Sampling operational, catalog written from LensTractor class
alternative command for sampleBall
minor maintenance
all versions of SDSS init.s in the same script
Cleaned up header doc
better SDSS cutouts
separate SDSS folders for lens and nebula, back to Phil's photocal
Tidied up, ready to start experimenting with variable point sources
Merge branch 'refactor' of github.com:davidwhogg/LensTractor into refactor
experimented with sampleball
Merge branch 'refactor' of github.com:davidwhogg/LensTractor into refactor

Conflicts:
	LensTractor.py
deleted copies of the script in sdss example folders
corrected typo in SDSS_IQ
mild improvement by thawing wcs
adjustment to SDSS var map when just sci is provided by user
LensTractor objects can now plot their own state
Refactored model initialization into model.py
Added placeholder code for spawning models from templates