warnings, changed the Curl_open() call as the second argument was never
used anyway

curl_global_cleanup().  Update corresponding man pages...

Improve the logic in curl_global_cleanup() and curl_global_init() so that
they are not called twice if the application libraries have been
initialized and make sure to reset the init flags in curl_global_cleanup().

This is my first CVS commit :), what it does:

- Makes sure that parts of the cURL library don't get initialized twice
- Makes sure that we only free what we initialize

specify exactly what global parts to init. Thanks to Sterling Hughes really
for arguing wisely.

curl_global_* functions

and download.h