Initialize the Simplified Chinese translation and make WxMaxima know about it
Completed about the first one-third part of zh_CN translation.
Completed GUI translation for zh_CN.

There are 785 translated messages in total.
Modified translation (zh_CN) for string "Load Package"
Merge pull request #237 from crickzhang1/master

GUI translation for simplified Chinese
Merge branch 'master' into insert-ans