Use UTF-8 consistently in lang strings
Use UTF-8 consistently in lang strings

In most places we call it "UTF-8". Changed two string
where "UTF8" where used.

Signed-off-by: Oscar Rydhé <2b3e17a7d6f527397936131db0874b14455019f5@gmail.com>

StealthWombat/SMF2.1-more-forkery,StealthWombat/SMF2.1-more-forkery