Make pipe_connection 'type' availble for all fluidboxes

[Klonan]

So for assembly machines, chemical plants, oil refinerys and small-pumps you can define the pipe_connection type, which shows up with little arrows on the 'detailed information' view

Like this

most of them have it defined by the production type of the fluid boxes, so the chemical plant has 4 fluid boxes, two defined as input, two defined as output, and on pipe connections they have either type = "input" or "output"

and with the small pump its just defined in the pipe_connections as "input" or "output"

But if you try using the same pipe_connection type with steam engines, pipes or storage tanks, the little arrows don't show up (i have actually only tried with steam-engine prototype)

It would be super helpful for showing where fluid connections are on sprites where it may not be immediately obvious, without having to use the pipe_covers as visual aid.

EDIT: as an aside, i thought the small pump use to show both an input and an output arrow, but for me at least it only shows the output now... maybe i'm mis-remembering

[Klonan]

This video demonstrates the problem i think a lot of people have

Video

It isnt clear in any part of the game where the fluid boxes are, and you can only tell my looking at the sprite.

Maybe an option for like 'highlight_pipe_connections = true" or something, which could help show where to put in the pipes (especially from ones on the 'back' of an entity where there are no pipe covers)

which could look something like this

Imagine the bars are blue not yellow