[algorithm] (new:minor) Added method 'count'
[math] (bug-fix:minor) Fixed doc typo
[math] (change:major) Deprecated 'min' and 'max' function and, to replace them, added 'definitely_min' and 'definitely_max' functions
[math] (new:major) Added new functional objects: 'approximately_less_equal','definitely_greater','definitely_less','definitely_max','definitely_min','essentially_greater_equal','essentially_less_equal'.
[text] Added Base64 encoder/decoder.
[debug] Added some to_string functions.