js type checks

git-svn-id: https://dev.geogebra.org/internal/moodle/moodle-qtype_geogebra/trunk@3046 872ce066-4876-4fca-a6fc-23b94bf576d1
move applet inject to mform.ggbt.init, correct null/type checks

git-svn-id: https://dev.geogebra.org/internal/moodle/moodle-qtype_geogebra/trunk@3048 872ce066-4876-4fca-a6fc-23b94bf576d1
new version

git-svn-id: https://dev.geogebra.org/internal/moodle/moodle-qtype_geogebra/trunk@3049 872ce066-4876-4fca-a6fc-23b94bf576d1
Merged from trunk
js type checks [from revision 3046]
move applet inject to mform.ggbt.init, correct null/type checks [from revision 3048]
new version [from revision 3049]

git-svn-id: https://dev.geogebra.org/internal/moodle/moodle-qtype_geogebra/branches/MOODLE_27_STABLE@3051 872ce066-4876-4fca-a6fc-23b94bf576d1