v4.0.1

Previously the ds3.c implementation had 26,346 lines, and 1,132,482 characters, which is unwieldy to traverse and some editors have trouble loading.

It has been broken down into 3 files, which should be completely transparent to SDK developers:

ds3.c:
client related methods
file utils for read / write from FILE
free methods for all struct types

ds3_init_requests.c:
enum to string
modify init request methods for all optional query params
init requests

ds3_requests.c:
metadata related methods
xml / parse helpers
xml request payload generators
xml response parsers
requests