Merge branch 'dev' with unit tests and bug fixes
Merge branch 'dev'
Added README_sky.md with sources and formats of of sky data
Merge branch 'master' into dev
Added xyrange subimage option to ex2d
Extraction bug fixes; testing; added regularization stub for ex2d
Merge branch 'ex2d' into dev
Changed util.psfbias formula (to be correct...)
more tests; cleanup
Merge branch 'ex2d' into dev
refactored xyrange; fixed tests
Merge branch 'cleanup' into dev
cleanup pixspline and add tests
Merge branch 'cleanup' into dev
Add absolute bias measurement function
Fixed flux units scale factor; added test to catch it in the future
Added input option checking; changed default CCD readnoise to 3.0
Merge branch 'multi_input' into dev