Enable save/load/import for day edit.

indra/newview/llenvironment.cpp

indra/newview/llenvironment.h

indra/newview/llfloatereditextdaycycle.cpp

indra/newview/llfloatereditextdaycycle.h

indra/newview/llinventorybridge.cpp

indra/newview/llviewermenu.cpp

...wview/skins/default/xui/en/floater_edit_ext_day_cycle.xml

indra/newview/tests/lldateutil_test.cpp

indra/newview/tests/llworldmap_test.cpp