User selected language is not always adhered to

[ddb4github]

Describe the bug
user_language is not took effect if user_language is different with browser locale

To Reproduce
Steps to reproduce the behavior:
0. Ensure browser locale is non-en-US, and change admin-->user_language to en_US
2. Access login page, check button, input-field stakeholder is not en-US
3. Login
4. Check top tab, top tab use 'non-en-US'
5. Check auth_profile.php?action=edit
6. User Language field is "English", but interface language is not English.

Expected behavior
A clear and concise description of what you expected to happen.

Screenshots
If applicable, add screenshots to help explain your problem.

[cigamit]

Can you please provide fresh pull request with the modified CHANGELOG for this an the other issue?

[cigamit]

Never mind, I did it.

[ddb4github]

More default behavior need to be completed: for case below

1. default auth_profile.php-->user_language is from settings-->i18n_default_language
2. default settings-->i18n_default_language is en_US
3. login page locale depend on browser interface language, e.g. non-en_US

Proposal story as

• Keep above #3 behavior, change #1 "default auth_profile.php-->user_language to browser UI language(locale)`
• Or Keep above #1, #2, and change #3 "login page locale always depend on settings-->i18n_default_language"

[netniV]

Personally, I believe that the order should be User Settings -> Browser -> System Settings. That way there is a fallback default language if the browsers language isn't supported.