catch boost locale conversion_error and add debug info

backports 
https://github.com/wesnoth/wesnoth/commit/9f798cb4f118869181297608c3b812c2118acab3
https://github.com/wesnoth/wesnoth/commit/f8dd7d6c87c838a98e03a83cf3a11109ebcbcada
https://github.com/wesnoth/wesnoth/commit/d9352503b2b93efb961f68736520dbfe5fc37334