Fix #476 Auto language changing function finished.

Fixes issue#476.
If the user does not have the freeseer.conf file, the function will detect the system location for default language.
If there is a config file, the language setting in that file will have higher priority.
For Chinese, If the location is not zh_CN, Traditional Chinese will be used.
If there is no translation for the system location, English will be used.
Since I does not consider the Location of the system when deciding which language to use (so fr_FR and fr_CH will be changed to fr_CA), there will be conflict on the two Chinese language. If I do not do the 'if case', all the Chinese system will choose Traditional Chinese because it lists after the Simplified Chinese in the loop.

About the high priority, it is because that for all the locations that use Chinese, only mainland China uses Simplified Chinese. TW, HK and some South East Asia countries use Traditional Chinese. So I set Traditional Chinese a higher priority and do a special judgement for zh_CN (mainland China).