[PATCH] Round instead of ceil/floor in the GUI

[elexis]

There are some rounding issues in the GUI:

• Trade carts can have very poor income, like 3 per trip. Since resources are floats however, the +10% upgrade might be actually useful in such a situation. So maybe the selection details could show two digits if the income is < 10.
• Some Hellenic buildings show +1HP due to some ceil(xxx.00002) (f.e. civic center 3301HP, house 1201HP, outpost 881HP, wooden tower 881CP).
• The ceil call for healthpoints was added so that there couldn't be a unit shown with "0" health points. So maybe we should use a round(HP) || 1 to account for that (r18009).

It seems floor/ceil should be abandoned altogether, but that needs to be investigated thoroughly considering the described edge case.