Enable Log file max size and log file rotation

[wuuti]

Currently the error.log keeps growing until eternity. This makes it useless somehow (the manager UI was pimped because auf this to allow only downloading from a certain size on - ugly IMHO).
I would like to have both a max log file size setting and the possibility to either truncate the log file or to archive older logs (and zip them).
This way even old logs would still be availabe (for research e.g. in case of hacking attacks), but the most recent log entries could still be shown in the manager reports.

[JensWolff]

@pixelfanatiker, @gerrit1986, @pepebe and @JensWolff are working on that

[gerrit1986]

ok

[gerrit1986]

error.log shouldn't be in a cache subfolder

[gerrit1986]

We could write a custom error handler as a replacement for modErrorHandler, hook it into the process by configuration and then use the custom handler as a proposal for a core enhancement: http://forums.modx.com/thread/29142/error-handling-and-error-logging-in-php-code-in-modx-revolution#dis-post-157488

[gerrit1986]

summary: created system setting for error_log's path, defaults to /logs, which is used by the logging. creating pull request for this.