Capture gstreamer errors in lib/PlayerVideo

[alanlivio]

When PlayerVideo have an error in gstreamer it make a fatal error to executable (see error bellow). All code in libginga should capture errors and only report to the it's user (eg. ginga-cmd, ginga-gui, ginga-qt). For instance, when this gstreamer have an error the ginga-gui die and the final user not know why. In this case, PlayerVideo should capture the gstreamer error and inform error to ginga-gui, which will not die and show the problem to the user.

$ ./src/ginga.exe -d examples/primeiro-joao/01sync.ncl (ginga.exe:8884): DEBUG: ginga::Formatter::setOptionDebug(): debug:=true (ginga.exe:8884): DEBUG: ginga::Formatter::setOptionExperimental(): experimental:=false (ginga.exe:8884): DEBUG: ginga::Formatter::setOptionOpenGL(): opengl:=false (ginga.exe:8884): DEBUG: ginga::Formatter::start(): examples/primeiro-joao/01sync.ncl (ginga.exe:8884): DEBUG: ginga::Context::afterTransition(): start root@lambda (ginga.exe:8884): DEBUG: ginga::Media::afterTransition(): start settings@lambda (ginga.exe:8884): DEBUG: ginga::PlayerVideo::start(): starting animation (ginga.exe:8884): DEBUG: ginga::Media::afterTransition(): start animation@lambda

(ginga.exe:8884): WARNING : ginga::PlayerVideo::cb_Bus(): No decoder available for type 'video/x-h264, stream-format=(string)byte-stream, alignment=(string)au, level=(string)3, profile=(string)high, width=(int)640, height=(int)480, framerate=(fraction)30000/1001, pixel-aspect-ratio=(fraction)1/1, interlace-mode=(string)progressive, parsed=(boolean)true'.

(ginga.exe:8884): ERROR : ginga::PlayerVideo::cb_Bus(): Your GStreamer installation is missing a plug-in.

[robertogerson]

Do we need this issue in the "Refactoring Release" ?