Add function and options for dictionary
- lvzstrings-mode.el (lvzstrings/dictionary-command): Add option for setting the dictionary shell command. (lvzstrings/lvzstrings-dictionary-keycomb): Add option for the keycombination for searching the selected word in dictionary. (lvzstrings/dictionary): Add method for searching the selected word in dictionary. (lvzstrings-mode): Add key combination for dictionary. (lvzstrings-mode): Add menu item for dictionary on lighter. (lvzstrings-mode): Add menu item for dictionary under tools/lvzstrings menu