Tools: po file validator

[ktyubeshi]

Script to verify that the po file meets the requirements of this project.

The script will load the file, apply the formatter, save, and then compare the differences with the loaded file.
I will also implement checks for errors that are likely to occur frequently and produce appropriate error messages.
Anticipated error patterns include:

• Unnecessary header items.
• Broken lines in msgid or msgtxt.
• Other errors (content doesn't match before and after applying the formatter).