Change GList->next calls to g_list_next(GList)
Make gswe_antiscion_axis_info_free() to unref its start_sign

This is to fix a bug that makes the library crash when the timestamp
or the chart changes.
Remove LUA example

LUA-LGI seems to be buggy with GLists (or I a too lame), thus the
example code cannot be reproduced in LUA yet.
Extend example programs