pingpong: Optimised the endofresp() function

Reworked the pp->endofresp() function so that the conndata, line and
line length are passed down to it just as with Curl_client_write()
rather than each implementation of the function having to query
these values.

Additionally changed the int return type to bool as this is more
representative of the function's usage.
pingpong.h: Fixed line length over 78 characters from b56c9eb48e3c
darwinssl: Fix send glitchiness with data > 32 or so KB

An ambiguity in the SSLWrite() documentation lead to a bad inference in the
code where we assumed SSLWrite() returned the amount of bytes written to
the socket, when that is not actually true; it returns the amount of data
that is buffered for writing to the socket if it returns errSSLWouldBlock.
Now darwinssl_send() returns CURLE_AGAIN if data is buffered but not written.

Reference URL: http://curl.haxx.se/mail/lib-2013-02/0145.html
email: Post optimisation of endofresp() tidy up

Removed unnecessary end of line check and return.
sasl: Fixed null pointer reference when decoding empty digest challenge

Fixed a null pointer reference when an empty challenge is passed to the
Curl_sasl_create_digest_md5_message() function.

Bug: http://sourceforge.net/p/curl/bugs/1193/
Reported by: Saran Neti
email: Another post optimisation of endofresp() tidy up
imap: Corrected a whitespace issue from previous commit

Fixed a small whitespace issue that crept in there in commit
508cdf4da4d7.
msvc IDE 'vc' directory tree preparation
move msvc IDE related files to 'vc' directory tree
install-sh: updated to support multiple source files as arguments

Version 7.29.0 uses Makefiles generated with a newer version of the
autotools than the previous 7.28.1. These Makefiles try to install
e.g. header files by calling install-sh with multiple source files as
arguments. The bundled install-sh is to old and does not support this.

The problem only occurs, if install-sh is actually being used, ie. the
platform install executable is to old or not usable. Example: Solaris
10.

The files install-sh and mkinstalldirs are now updated with the automake
1.11.3 versions. A better fix might be to completely remove them from
git and force the files to be added/created during buildconf.

Bug: http://curl.haxx.se/bug/view.cgi?id=1195
Reported by: Rainer Jung
move msvc IDE related files to 'vs' directory tree

Use 'vs' directory tree given that 'vc' intended one clashes
with an already existing build target in file Makefile.dist.
smtp: Removed duplicate pingpong structure initialisation

The smtp_connect() function was setting the member variables of the
pingpong structure twice, once before calling Curl_pp_init() and once
after!
email: Tidy up before additional IMAP work

Replaced two explicit comparisons of CURLE_OK with boolean alternatives.

General tidy up of comments.