Added preliminary support for the KIDS survey.
Added a command-line parameter to specify the survey.
Added KIDSWCS, KIDS_photocal and KIDS_epoch, corresponding to there
PS1 counterparts.
Improved the support for multiple surveys, in particular KIDS.
Merge branch 'kidssupport' into develop
Added KiDS support:
- Added --survey argument to LensTractor.py
- Created kids.py with the following functions:
  - KIDSWCS, KIDS_IQ, KIDS_photocal, KIDS_epoch
- Added kids.py to __init__.py
- Added survey support for photcal and epoch in dm.py
- Added KiDS support to dm.py
Added KiDS support:
- Added --survey argument to LensTractor.py
- Created kids.py with the following functions:
  - KIDSWCS, KIDS_IQ, KIDS_photocal, KIDS_epoch
- Added kids.py to __init__.py
- Added survey support for photcal and epoch in dm.py
- Added KiDS support to dm.py