locale-selectable install script

1. set utf8-related collation for its database (3485392)
https://sourceforge.net/tracker/?func=detail&aid=3485392&group_id=66479&atid=514646

2. implementing multi-byte processing into its whole core (3485393)
https://sourceforge.net/tracker/?func=detail&aid=3485393&group_id=66479&atid=514646

3. allow to import skins encoded by the other character encoding schemes than ISO-8859-1/US-ASCII/UTF-8 (3485395)
https://sourceforge.net/tracker/?func=detail&aid=3485395&group_id=66479&atid=514646

4. make a rule for dealing with locales and arranging translation files following to it (3485396)
https://sourceforge.net/tracker/?func=detail&aid=3485396&group_id=66479&atid=514646

5. separate the decision process of character encoding scheme and locale (3485397)
https://sourceforge.net/tracker/?func=detail&aid=3485397&group_id=66479&atid=514646

With the close of these ticket, Nucleus CMS can deal with multi-language. But we cannot select our favorite locales in its installing process. The install script should be improved till 4.0 release.