add check for same image (then skip it and reload next)
modified:   Makefile: upgrade version to developpement one; add -O0 option or fast compilation.
modified:   VERSION: v0.2.0.dev .
modified:   _info.txt: add test example command line (for internal 5Hz camera).
modified:   grab.cpp: change CImg to CImgList container for comparison of current and previous loaded frame (if entire frame have same pixels, then reload).
modified:   grab.help.output: autoupdated by make.
setup faster comparison for current and previous grab image.
modified:   Makefile: setup optimisation level 3 for gcc.
modified:   _info.txt: add Elphel curl setup command lines.
modified:   grab.cpp: comparison of current and previous grab images using 3x3 pixel area.
modified:   grab.help.output: auto updated.
add live display and no save (-c option)
modified:   grab.cpp: add live display: continuous display and static display on P or S key (besides in this live mode: infinite loop and saving disabled).
modified:   grab.help.output: auto updated.