Replaced the use of CURLOPT_USERPWD for the preferred CURLOPT_USERNAME
and CURLOPT_PASSWORD options and used the same username and password for
all email examples which is the same as that used in the test suite.
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.
An example application source code sending SMTP mail with the multi
interface. It is based on the code Alona Rossen provided, which in turn
is based on existing example/test code, and I converted it even more
into a decent example with a fair multi API use, put the info required
to edit at the top and I added some comments.
