Fix spell check language.
I am on a non English based system, and when spell check starts it uses
by default my language that is not English.
This fix should work on Linux and Mac OS. I doubt it will work on
Windows, but anyway spellcheck.sh is a development tool and the base of
our developers are on Unix based systems.
Merge pull request #296 from thdox/fix-lang-when-spellcheck

Fix spell check language.