ua.php: fix $_digits female part, correct $_minus

Minor text correction: $_digits array contained male gender texts where female gender needs to be. I.e. it is currently «один тисяча» «два тисячі» which should be «одна тисяча», «дві тисячі» respectively. Also, minus іs «мінус» in Ukrainian, not «минус».
Some more text fixes to ua.php

After a closer view, Ukrainian translation is just a copy of Russian with currency names in Russian and some of them just plain incorrect, like piastres instead of kurushes in TRL.
More ua.php fixes

Double-checked some.
Merge pull request #20 from matvey-andreyev/patch-1

ua.php: fix $_digits female part, correct $_minus