FIX: bad new buffer handling for string! to UTF-8 conversion.

Buffer size allocation now bigger to avoid overflows. Still the most accurate way is precalculating the size of the UTF-8 output like done by Oldes in the `float` branch.
FIX: issue #861 (Handling float! pointer argument incorrectly in function on Linux-ARM)
Merge branch 'master' of github.com:red/red