[PATCH] Trading Waypoints (2-parter)

[michael]

1. Trade units can be tasked by the player to multiple waypoints on their journey, so that they avoide collisions, obstacles, or battlefields.

2. Trade units could waypoint between multiple markets/docks (3 or more), for a 10%-ish trading bonus for each additional market/dock. Dropped after some discussion (easily exploitable or if that is fixed hard to make obvious to the player)

[leper]

Trade with more than two markets (WIP missing code to display proper stuff in the gui)

[leper]

I attached a patch that implements point 1, 2 and #1821 and #1822 (with a small remaining TODO in RallyPointCommands.js). There is some code missing in GuiInterface.js so that the tooltips display something, but after some discussion of point 2 in IRC we decided to remove that. I'm just attaching this patch in case someone wants to do something like that in the future.

[mimo]

Here is a patch for #1207, fixing at the same time #1821 and #1822. The patch is also a first step in the implementation of trading in formation (where we could have a column formation for traders), but this last feature is not completely implemented for the time being because of problems with the path finder for ship formations which prevent walking in formation for merchant ships.

[mimo]

In 14697:

allow the possibility to define route with waypoints when doing trade, fixes #1207, #1821 and #1822