int firestring_estr_base64_encode(struct firestring_estr_t *destination, struct firestring_estr_t *source)
firestring_estr_base64_encode() encodes the contents of
using the base64 algorithm into
provided that there is room in
The minimum required space in destination is the length of source * 4 / 3 + 4.
0 if the string was encoded successfully; 1 if there was insufficient space in
for the encoding to occur.