[wp-polyglots] Common Mistakes

[Morgan Doocy]

I've been seeing a lot of PO files making the same two mistakes, so I  
went through the repository and corrected all instances of them.  
Corrections made were as follows:

- zh_CH: removed all ↵ and • characters. Note that I could not recreate  
the MO file, because line 213-214 is missing the translation for "New  
user registration on your blog %1$s\n". Also removed "_*_abbreviation"  
from the month abbreviation translations, and "_*_initial" from the  
weekday initial translations. (Note that these still aren't actually  
translated, the message strings had just been copied literally.)

- de_DE, cs_CZ, fi_FI: removed "_*_abbreviation" from the month  
abbreviation translations, and "_*_initial" from the weekday initial  
translations.

- sv_SE: removed "_*_abbreviation" from the month abbreviation  
translations.

- it_IT: removed two ↵'s

Explanations:
- "*_*_abbreviation":  
http://codex.wordpress.org/Localizing_WordPress#Month_abbreviations
- "*_*_initial":  
http://codex.wordpress.org/Localizing_WordPress#Weekday_initials
- ↵ and • in Rosetta:  
http://codex.wordpress.org/ 
Localizing_WordPress#Translating_with_Rosetta (just added now)

With the exception of zh_CN, I regenerated all MO files for those  
locales that were corrected.

Morgan