Fixed errors with gcc -fno-common option.

Fixed severe regression in double image mode where the measurement image filename would be copied from the detection image filename (thanks B.Yanny).

Fixed byte-swapping flag issue with -fno-common compilation flag.

Fixed building issues with Ubuntu Xenial.
Fixed DEB parallel building issue.

Fix citation

Doc: Moved FLUX_ISO and CLASS_STAR to isophotal measurement section (which is still named Position.rst, for portability reasons).
Doc: Added ISOAREA description in isophotal shape section.

Doc: Fixed broken ref to Background Modeling section.

Doc: added description of aperture FLUXERR in photometry section.

Doc: Added description on FLUX_PETRO in Photometry section. Re-wrote part of the FLUX_AUTO subsection to better describe "reduced pseudo-radii".

Doc: added Flagging section and flag description tables in Windowed measurement and Weighting sections.