Percentage spinners (e.g. zoom selector) should be localizable

[Adolfo Jayme Barrientos]

Some languages (such as German, French, Slovenian and Spanish) should display the percent sign separated from the number by a space. (12 %)
Others (such as Turkish and Basque) display it before the number (%13 or % 14).
This is an issue that should be handled per locale in a more low-level library, but that’s an utopia.

[Cameron White (cameronwhite91)]

I think I've got this working with https://github.com/PintaProject/Pinta/commit/037c7cf7000305cac38cf80f7b13f7941d170838

[grofaty (grofaty)]

I don't think this is fixed. See above two attachments for detailed explanation. In short, for Slovenian there should be space between number and percentage character.

[Cameron White (cameronwhite91)]

The current implementation just uses the standard percent format specifier (https://msdn.microsoft.com/en-us/library/dwhawy9k%28v=vs.110%29.aspx#PFormatString). Since that doesn't seem to be correct for some locales, I think we'll need to add a translatable string so that the percent sign can be formatted correctly for each language.

[Cameron White (cameronwhite91)]

Fixed: https://github.com/PintaProject/Pinta/commit/7653dd178e134c761830b34b97e139e36f519238

There is now a translatable string for how to format the zoom percentage. Although I said we are in a string freeze, I think adding this one is ok since the untranslated version is no different than what we had in Pinta previously.