Various editor fixes. Start adding a settings picker.

indra/llinventory/llsettingsbase.cpp

indra/llinventory/llsettingsbase.h

indra/llinventory/llsettingsdaycycle.cpp

indra/llinventory/llsettingsdaycycle.h

indra/newview/llfloatereditextdaycycle.cpp

indra/newview/llfloatereditextdaycycle.h

indra/newview/llviewerfloaterreg.cpp

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

.../newview/skins/default/xui/en/floater_settings_picker.xml