Always return all-bands reference fluxes for matched sources.
Imporve robustness of astrometric match.

C++ side:
 1. Increase number of sources to define the shape to match from 5 to 6.
 2. Store up to 3 match list candidates and return a list with most matches.
 3. Even when the number of matches is smaller than requested,
    return a list with most matches.

python side:
 1. Check prefix and use that prefix when checking saturation.
 2. Try macthing both with and without saturated sources.
    A matched list with more unsaturated sources will be selected.
 3. Even when the number of matches is smaller than requested,
    returned list will be used with a warning message.
SConstruct: remove Mercurial
Further parameters tuning.
Some parameters are now configurable.
Merge branch 'master' of ssh://hsc-repo.mtk.nao.ac.jp:10022//home/gituser/repositories/hscAstrom
Do not use sources detected in EDGE or NO_DATA area for matching.