Add ability to search from descriptions

[mikkokotila]

Background

So far it is possible to search based on keys (Tibetan words), here we will make it possible to also search based on values (descriptions for Tibetan words). It will work similarly to partial, fuzzy, and similar in the sense that it will force to select a single dictionary where the search is performed. But it will be different in the sense that instead of becoming available in the search button, it becomes available as its own menu item.

How will it work?

• [x] Add back the navigation with items Tibetan, Description
• [x] Tibetan does what the dictionary does now
• [x] Description works otherwise the same as Tibetan but it will look for a match from descriptions
• [x] Description is enabled through matching=description argument in the API
• [x] Once Description is enabled, the search button only has Partial match option
• [x] Upon selecting Description, the prompt for selecting just one dictionary is shown

[rabtenster]

@mikkokotila Once Description is enabled, the search button only has Partial match option : This line is confusing as currently we have four matching modes where partial is one, now when description is also enabled by adding a new matching mode , then having partial match option for description confuses as matching = description and not partial. Maybe I didn't get it properly can you shed some more light on it. I think simplest is adding description as new matching mode from the search dropdown and force to select one dictionary.