Improve search for chat messages

[mahibi]

The message search was never implemented sufficiently.

A user does not always get the result he is looking for, i.e. the message he is looking for is sometimes not found in the chat.

The overview will show the matched results, but when clicking on a result it depends if the message is available in the adapter.

For older messages this is most likely not the case (one would have to scroll very often upwards before searching to have a chance it's included in the adapter), so only the last messages of the chat are shown instead to show the searched message.

Loading all messages into the adapter at once is not an option for performance reasons. Same for doing it in a loop. (It may differ if the message is found in the database for the latest chatblock. Then it might be an option to load a lot of data into the adapter, as it's quicker than doing online requests in a loop. But this might also have limitations).

Talk iOS seems to have the same challenge. The workaround there is to show a snippet of the chat in a search window. So there the searched message is shown and maybe 30(?) messages are shown before and after it, without being able to scroll further.
For talk android this would mean that chatblocks may be created that are not connected to the latest chatblock. This shouldn't be a problem when there is no option to scroll in the search result window.

We should implement the same for android talk or discuss if there are other ways to solve it.