the curl_easy_strerror() function to provide one

defined (which it never is atm).

Now, we can focus on making 'runtests -t [num]' work on all test cases and
we should never leak nor crash.

accordingly

from 64 bit types to 32 bit ones

curlx_-functions with the new prefix to prepare this code for the future
removal of several curl_-functions from the public libcurl API.

in alphabetical order

concept, and added lib/README.curlx to explain details about it

such platforms that support large files.

machines.

libcurl *printf and by Linux printf(). This should make the code work nicely
even for 64bit size_ts.

limit-rate. It does work on the expense of the rate limiter.

officially using library-code when building the app (at least for the platforms
that don't have a strtoll() on their own).

This is made to prevent compiler warnings.