Update to the SuperTuxKart source strings

[Alayan]

The source strings for the game's translation have been updated on Transifex. Languages that were previously 100% translated are now 88,87% translated.

Changes include:
- Translation for the STK server messages used during log in
- Translation for the names of STK's default skins
- Translation for the server answers to server commands in the server lobby (and much improved base messages in english)
- Contextual translation for several words that needed it (most notably "Medium" which could be a kart class, a font size, a graphics setting...)
- Removal of raw URLs from translatable strings
- Some other new strings and various small string fixes

Information about how to help translating STK is available here. 

We had some cases previously of low-quality translations that ended up wasting our time, so please only contribute if you have a solid grasp of English and your chosen language. 

If you notice issues in the source strings that need to be translated, please let me know!

[Tuxito3000]

I'd like to help with the Spanish translation (it's my language), but it's asking for a business email address. How do I do that? :p

[Alayan]

I notice I didn't answer earlier. I suppose you figured it out, but you should be able to use any email address to sign up to Transifex to become a translator. However I think in some contexts the email address may be shown (team managers can see them, not sure if it's anywhere in the translation credits).

In general, it's good practice to have some separation between email addresses depending on the main use cases (don't use the same email address for your banking stuff and for gaming stuff for example), it helps to reduce tracking and reduce the attack surface for malicious actors.

[GustaLOLE]

I started to translate various strings to Brazilian Portuguese today.

I guess I translated more or less 55% of the untranslated strings.

[GustaLOLE]

I started to translate various strings to Brazilian Portuguese today.

I guess I translated more or less 55% of the untranslated strings.

I finished this
Next week, I gonna start the revision of the rest of the strings.

[Alayan]

It's quite cool you put in time to help on translations.

That being said, my understanding regarding language variants is that by default they use the same string as the main language if there is not a specific translation.

At least, that's how the Canadian French variant (which replaces "Football" with "Soccer") works, so I'd assume it'd be the same for things such as Portuguese vs Brazilian Portuguese or American English vs British English.

In other words, "variants" only really need to translate a string if there is a difference between both languages for it ; such as a different word being more natural (like the football / soccer example), or a different way to spell a word present in the translation.

I'm bringing this up, because while translating everything for the variant would still work fine in-game, there are two potential issues:
- Duplication of effort (extra work that doesn't actually make things better)
- Desynchronization of translations (a string which really ought to be translated the same way in both cases being made different). This increases the risk of mistakes (typos, poor choice of translation) and in cases where the new strings get a better translation, the base language ends up missing on the improvement.