Solution: Extract generic find function

* Problem: boilerplate when init msg from data copy

Solution: Add zmq_msg_init_buffer to construct
a message by copying memory from buffer.

Problem: Strange zmq_poller doc formatting

Solution: Add newlines and extra asterisks

Problem: zmq_send doc does not match declaration

Solution: add const to pointer type

Problem: ZMQ_THREAD_SAFE is not bool

Solution: Change documentation value type to int

Fix gitignore tracking file list

Solution: Fix .gitignore's exceptions for sources in tools/

Install CMake config to LIBDIR by default, to correctly support multiarch

Signed-off-by: FeRD (Frank Dana) <ferdnyc@gmail.com>

Solution: Install CMake config in arch-dependent LIBDIR/cmake

Using "share/cmake/${PROJECT_NAME}" as DESTINATION for installing
ZeroMQConfig.cmake et al works for arch-independent configs, but
is wrong for multiarch. The configs for each version of the
library should be stored below the arch-dependent LIBDIR, using
the GNUInstallDirs ${CMAKE_INSTALL_LIBDIR} variable.
Signed-off-by: FeRD (Frank Dana) <ferdnyc@gmail.com>

Refactor protocol literals into constants

Some ifdefs in condition checking may cause problem in some compiler or
static analyzers. When PGM and NORM both are disabled, some condition
will be derived as false || false.

Solution: Splitted condition checking for every ifdef conditions

Conditinoal compile for OPENPGM and NORM is mixed.
Also found few codes which needs conditional compile but not applied.

Solution: Apply conditional compile preprocessors

Solution: replace into named constants

Optimizing gitignore files

Solution: optimize gitigore using patterns
 *  Categorize ignoring lists
 *  Use pattern to remove similar lists
 *  Marked source files to be tracked

Problem: msg_t functions do not respect coding style

Solution: fix them

Add UDP transport to related docs

* UDP is mentioned as available transport, and it also supports
  wildcard addresses, but not mentioned
* zmq_unbind(7) also mentions about wild-card endpoint in zmq_bind(3)

Solution: add udp in wildcard address related docs

zmq_bind(3) and zmq_connect(3) does not mention UDP as available
transport types.

Solution: add udp mentioning line for related docs

Problem: building on OS X may failed

Solution: Add troubleshooting guidelines to resolve

(Relicensing statement added)

* ip_resolver_t: adding virtual descructor to silence C++-warning -Wnon-virtual-dtor

* adding my relicense

News out of date, formatting not clean

Solution: run make clang-format-diff

Solution: update it

Solution: add it

* add option to stop trying to reconnect on ECONNREFUSED

Fix unused-variable warning in perf/proxy_thr.cpp

Add relicense grant by Laszlo Boszormenyi (GCS)