No more use exit(3) but instead tell libcurl that no byte has been
written to let it return a `CURLE_WRITE_ERROR`. In addition, check
curl easy handle return code.
All C and H files now (should) feature the proper project curl source
code header, which includes basic info, a copyright statement and some
basic disclaimers.
1. Remove the comment warning that it's "not been verified to work". It
works with no problems in my testing.
2. Remove 2 unnecessary includes.
3. Remove the myrealloc(). Initialize chunk.memory with malloc() instead
of NULL. The comments for these two parts contradicted each other.
4. Handle out of memory from realloc() instead of continuing.
5. Print a brief status message at the end.
