Fix typo in self._chinese_mode variable

When porting to GObjectIntrospection, I made a typing mistake
in the self._chinese_mode variable. This caused a problem when
the dconf key for “chinesemode” was not yet set. Then the property
for selecting the Chinese mode in the ibus menu was empty and
and selecting the empty line with the mouse just caused an error.

This commit fixes this.
When detecting the Chinese mode from the environment, also check LC_ALL

LC_ALL has even higher priority then LC_CTYPE and should be checked
first.
Merge pull request #4 from mike-fabian/mike-fix-typo-in-chinese-mode-variable

Mike fix typo in chinese mode variable