Added macro to allow simpler logic in functions with the need to vsnprintf
Replaced vsnprintf with VAFORMAT pretty much everywhere.
Move LogLevel enum from filelogger to logger.
Move LogHeader to LogStream.
Purge a ton of code related to non <log> related logging.

- InspIRCd::OpenLog
- ./inspircd --logfile [file]

This is no longer needed now we have (since 1.2) custom logging.
Accept a LogLevel instead of an int in logging methods.
Fix spacing in calls to LogManager::Log.
Merge pull request #542 from ShutterQuick/inspircd+printfcleanup

Replaced all the individual vsnprintfing with a macro
Fixup last commit
Remove OnUserPreNotice and OnUserNotice hooks, add MessageType argument to OnUserMessage and OnUserPreMessage

All modules (except m_nonotice) that perform filtering on messages have common logic for handling PRIVMSGs and NOTICEs and most of them run the exact same code in both cases
Add support for detecting C++11 variadic templates.
Merge pull request #548 from SaberUK/master+variadic-templates

Add support for detecting C++11 variadic templates.
Fix msvc detection of variadic template support
Convert XLine::Displayable to return a std::string.
Merge pull request #522 from SaberUK/master+xline-displayable

Convert XLine::Displayable to return a std::string.
Merge pull request #545 from SaberUK/master+logging-cleanup

Clean up the logging system (part 1 of 2).
Change CacheRefreshTimer tick time back to 5 minutes
Some systems with whacky va_list implementations do undefined stuff when vsnprintf is called multiple times with the same list, so have InspIRCd::Format va_copy the list before each call
Add a va_copy define for Windows
Remove dead ModeParser code