Makefile.in: add LIBS handling

In the autoconf universe LDFLAGS are used for all linker flags, and
LIBS are used to specify additional libraries. Autosetup has support
for that but Makefile.in needs to honour them too.

Signed-off-by: Paul Fertser <fercerpav@gmail.com>
Add md5 command.
Add base64 command.
Add totp / hotp command for One-Time Password generation.
Add rudimentary tests for md5 and base64.
Add rudimentary ØMQ command.
Remove unused SEND_BUFFER_SIZE define.
Revise and add the modules aes, base64, hex, md5, thotp, z85, zeromq.

This commit includes tests and some examples.
Fixed some memory leaks.
Add some more comments to the zeromq examples.
Add support for DEALER, ROUTER and PAIR flag.
Add zeromq inproc example.
Increment reference count on version string.

It seems the version string gets garbage collected otherwise
and `package require foo` returns a currupted version string.
Remove forced version string for compiled extensions.

The package loader handles a missing `package provide` already.
Remove unused defines.
Add ZMQ_STREAM, although it work only in one direction for now.
Remove superfluous EVP_EncryptInit_ex and EVP_DecryptInit_ex call.
Add more AES modes and tweak settings.
Add pwd to autopath and provide a Tcl package.
Free received message.
Remove ROUTER and DEALER as they probably won't work.