[Suggestion/QoL] Exclusion filters for trade goods

[azaghal]

The trade offers displayed on the map will often get filled-up with various wares that the player is not interested in trading, such as energy cells, meat, wheat, water etc - in general wares which are abundant and/or provide for very low profit margins/absolute incomes.

While the player can apply positive filters to pick a particular ware, it would be nice if it were possible to also apply negative filters that exclude a particular item instead. This would be especially helpful in situations where player is not quite sure what specific ware would be profitable, and is going through the process of elimination instead.

To specify the negative filter, the player would do one of the following:

• Type in exclamation mark (!) in front of the search term in the search box. For example: !water.
• Use CTRL + Left Mouse Button Click on the ware in the auto-complete popup (which is shown while typing in a search term in the search box).
• Use CTRL + Left Mouse Button Click on the ware filter below the search box to toggle the filter as positive/negative.
• Use CTRL + Left Mouse Button Click on the ware in the expanded "Trade Filters" tab on the right side of the screen (necessary when you have more than five items in the list).
• Use CTRL + Left Mouse Button Click on the ware name shown on the map, in ship manifest, information tab etc.

P.S.
Similar functionality could be extended to other filters as well (sector names, free-form strings) when using the search box.

P.S.S.
Ergonomically (tm), initially I had the idea of using Right Mouse Button Click for search box parts, but that would "interfere" with some of the existing conventions in the GUI (accessing the trade menu for specific ware in a station/build storage).