Another Log implementation

[Vincent]

Small work on issues: http://pastebin.com/fd3UCgjv

As you see, there is no more 'version' spaghetti:

auto logDbg = new Log(new FileLogEngine(`c:\res.txt`), new  
DBLogEngine(``));
auto logErr = new Log();

logDbg(`It works for %s`, `me!`);// won't be printed if '-version=log' is  
not specified
logErr(`Serious problem!`);