formdata.c:390: warning: cast from pointer to integer of different size

Introduced in commit ca5f9341 this happens because a char*, which is
32-bits wide in 32-bit land, is being cast to a curl_off_t which is
64-bits wide where 64-bit integers are supported by the compiler.

This doesn't happen in 64-bit land as a pointer is the same size as a
curl_off_t.

This fix doesn't address the fact that a 64-bit value cannot be used
for CURLFORM_CONTENTLEN when set in a form array and compiled on a
32-bit platforms, it does at least suppress the compilation warning.

The OpenSSL API change that broke this is "Convert ERR_STATE to new
multi-threading API": openssl commit 8509dcc.

Closes #713

follow-up to 80015cdd

... to allow users to see which specfic wildcard that matched when such
is used.

Also minor logic cleanup to simplify the code, and I removed all tabs
from verbose strings.

It would also seem that share.h is not required here either as there
are no references to the Curl_share structure or functions.

Bug: https://curl.haxx.se/mail/lib-2016-03/0150.html
Reported-by: Oliver Graute

... to allow torture tests then too.

As just discussed on the mailing list, also document how we prefer
spacing in expressions.

cppcheck warned:

[src/tool_urlglob.c:283]: (style) Checking if unsigned variable 'step_n'
is less than zero.

Ripped out from CONTRIBUTE into its own document, but also extended from
there.

Since sh_getentry() now checks for invalid sockets itself and by
narrowing the scope of the remove_sock_from_hash variable.

Simplify the code by using a single entry that looks for a socket in the
socket hash. As indicated in #712, the code looked for CURL_SOCKET_BAD
at some point and that is ineffective/wrong and this makes it easier to
avoid that.

Closes #712

Closes #703

Rather than use a 0 and 1 integer base result code use a TRUE / FALSE
based success code.

Rather than use 0 and 1 integer base result codes use a FALSE / TRUE
based success code.

warning C4267: 'function': conversion from 'size_t' to 'int',
               possible loss of data