Implement support for non-breaking spaces

[GunChleoc]

We have requests from 2 languages not to implement support for non-breaking spaces. Since boost::format can't handle the Unicode character, we should go with HTML code:  

[Hans Joachim Desserud (hjd)]

Could you provide some context what sort of problems these languages run into and how non-breaking spaces solve them?

Just curious :)

[wl-zocker (wl-zocker)]

German:
Abbreviations that consist of several letters should have a non-breaking space between them: It should be "z.&nbspB." (which means "for example"). I am not sure if this is used inside Widelands.

French:
They use a lot of non-breaking spaces before and after punctuation mark. Some examples: « Quoi ? » (I'm no native speaker, but you got the idea.)

Many languages:
- To avoid the splitting of "5 minutes" or "3 soldiers" at the end of a line.
- For the calculation example used in the second tutorial (I think it was there). Here, I would have liked non-breaking spaces between the operators and the numbers.

[GunChleoc (gunchleoc)]

Also, it would be good to habe a non-breaking hyphen for Scpttish Gaelic, because we have t-, h- etc. in front of words that shoudldn't be split. However, we son't split at hyphens yet, so this isn't relevant at the moment. IMO we should have a general entity to Unicode conversion capability.

[GunChleoc (gunchleoc)]

Fixed in build19-rc1.