Better no threads found message

[hardeepasrani]

The following message right now appears when no threads are found in Forum (like a plugin/theme's support forum/review:

Oh bother! No topics were found here!

It should be some thing helpful, like:

Looks like what you were looking for couldn't be found! You can always create a new thread.

Hope it makes sense.

[SergeyBiryukov]

Let's get a consensus on the wording at the next Support Team meeting.

[macmanx]

After some great discussion in the Support Team meeting, we rallied around something like "No topics found. Try a different search or start a new post."

It gets the message across simply without any cultural limerick like "Oh bother!" (and is thus easier to translate), and offers two simple suggestions for what to do next.

[SergeyBiryukov]

There are four distinct "Oh, bother!" messages:

• "Oh, bother! No forums were found here." — unlikely to be seen once forums are created.
• "Oh, bother! No replies were found here." — only displayed for bb_base_reply_search_query() (?rs=...). Unlikely to be seen, as there is no UI for that.
• "Oh, bother! No search results were found here." — only displayed on Rosetta forums, as English forums use Google search.
• "Oh, bother! No topics were found here." — only displayed in empty views, mainly Spam/Pending/modlook, unlikely to be seen by non-moderators. Also displayed in plugin/theme reviews in there are none.

Seems like only the latter two should be changed. Suggestions:

• Search results: "No results found. Try a different search or start a new post."
• Empty view: "No topics found. Select another view or start a new post."

[SergeyBiryukov]

In 5019:

Support Theme: Improve the message displayed when no topics are found to make it more helpful and avoid cultural references.

• Search results: "No results found. Try a different search or start a new post."
• Empty view: "No topics found. Select another view or start a new post."

Props hardeepasrani, macmanx, zoonini, kenshino, clorith.
Fixes #2006.