Add tooltip for pump down buttons on info view

[impaktor]

Do we want this?
I've added it because I can never remember how these buttons work, which might be an indication there's a deeper UI issue.

Anyway, if we want it I can clean this up and add it to localization. Looks like so now:

tooltip.mp4

ping @bszlrd & @sturnclaw

[fluffyfreak]

More tooltips is generally more betterer 😉I think it's helpful

[bszlrd]

I agree with Fluffy, the more tooltips, the better.

[sturnclaw]

Grug say "many tooltip, more knowledge".

(The tooltip should probably say "Pump X t of fuel to/from cargo".)

[impaktor]

OK, done.
Ready for review.

tooltip.mp4

[Bodasey]

Any other open source user here who can not watch these videos? (file corrupt)

I've added it because I can never remember how these buttons work, which might be an indication there's a deeper UI issue.

Yes, these arrows are contra-intuitive...some suggestions how it might be better? These arrows always indicate the direction of fuel flow:

I have added the signs +- as suggestion in the second draft to have the same look as in the commodity market, but then, the text was better "from Cargo bay".

[craigo-]

I like the numbers on the buttons, I hope they remain.

Suggestion:

• Place a single "<" (or another existing arrow equivalent) before the word "Refuel" to indicate direction
• Place a single ">" (or another existing arrow equivalent) before the phrase "Pump down" to indicate direction
• Keep the numbers on the buttons, but remove the negative sign for the "Pump down" options