DDMsgReader: Added "indexed" reader mode and made a fix to print utf-8 characters properly on non utf-8 terminals. Fixes issue #354 and issue #541

DDMsgReader: Added "indexed" reader mode and made a fix to print utf-8 characters properly on non utf-8 terminals. Fixes issue #354 (closed) and issue #541 (closed)

Note that this includes an updated dd_lightbar_menu.js (for sbbs/exec/load). The most significant update in dd_lightbar_menu is that a DDLightbarMenu can now include non-selectable items. Such items will be skipped when scrolling through the menu.