ConfigManager: Ensure key files are loaded and saved as utf-8

git-svn-id: svn+ssh://svn.code.sf.net/p/gramps/code/trunk@21447 4ae1f11a-8b86-4847-b8af-ab372f36d1fd
grampletpane: Use __future__.unicode_literals instead of cuni()

And get rid of the silly NL = "\n"

git-svn-id: svn+ssh://svn.code.sf.net/p/gramps/code/trunk@21448 4ae1f11a-8b86-4847-b8af-ab372f36d1fd
grampletpane: Replace diagnostic prints with log warnings.

And improve warning when unable to save the Dashboard layout.

git-svn-id: svn+ssh://svn.code.sf.net/p/gramps/code/trunk@21449 4ae1f11a-8b86-4847-b8af-ab372f36d1fd
Addons: Check for two-letter lang as well as 5-char locale

E.g, check fr as well as fr_FR

git-svn-id: svn+ssh://svn.code.sf.net/p/gramps/code/trunk@21450 4ae1f11a-8b86-4847-b8af-ab372f36d1fd
GrampsLocale: Remove all calls to locale.setlocale and locale.bindtextdomain

git-svn-id: svn+ssh://svn.code.sf.net/p/gramps/code/trunk@21451 4ae1f11a-8b86-4847-b8af-ab372f36d1fd