m_ssl_gnutls Fix feature testing and cipher suite related errors on older GnuTLS versions

Use the (old) LIBGNUTLS_VERSION_* defines as a fallback when GNUTLS_VERSION_* is unavailable

Fixes #595 reported by @rhylan
m_dnsbl Fix possible use-after-free after a rehash
m_spanningtree When an IOHook goes away close all pending connections that use it
Update example configs, README.md and more

- Fix typos, remove misleading information, rephrase a few sentences
- Add info about hmac-<hash> hash types
- Remove <performance:maxwho> (the code which used this was removed in 96e4434 - @SaberUK)
- Change inspircd.github.org to inspircd.org
m_permchannels Construct the final line that will be saved in a std::string in WriteDatabase()
m_permchannels Save channel TS, topic set time and set by information

When loading, ignore and log channels with a name longer than Limits.MaxChan
m_permchannels Add the ability to save listmodes
Fix crash caused by passing a large integer to ctime()

In addition to verifying the return value of localtime(), correct tm_year if it is out of bounds

Reported by @JDowny
Fix fd and minor memory leak in threadengine_pthread on unload of m_mysql
Update COPYING file with new FSF address.

This should make rpmlint stop complaining about the incorrect FSF
address. All changes taken from:
    http://www.gnu.org/licenses/old-licenses/gpl-2.0.txt
m_permchannels Fix empty topic setby
Release 2.0.14
Don't CoreExport reference, fixes m_dnsbl on Windows

The explicit instantiations of reference are now useless; remove
Improve support for rarely used compilers, EKOPath in this case.
m_spanningtree Fix timestamp in AWAY
Merge pull request #623 from ChrisTX/insp20+compilerfixes

Improve support for rarely used compilers, EKOPath in this case.
Fix a crash when running as systemd service

- Fix a NULL dereference if a signal is raised in the constructor of the
class InspIRCd
- Resolve the parent's process exit code being SIGTERM=15 and typically not
EXIT_SUCCESS thus

A combination of the two caused crashes when running as systemd unit.
m_showwhois Require 2 parameters for WHOISNOTICE
m_httpd Close all open http sockets on unload
Fix a shadow warning created by ConfigTag::create