configure: look for libboost_unit_test_framework-mt

as well as libboost_unit_test_framework.
Work around missing std::to_string on Cygwin

http://stackoverflow.com/questions/22571838/gcc-4-8-1-stdto-string-error
Support Cygwin platform
Update ChangeLog
Avoid obsolete ToFileName[]
Merge branch 'feature-cygwin-support' into development