Replace logging backend to log4rs and add log rotation (#1789)

* Replace logging backend to flexi-logger and add log rotation
* Changed flexi_logger to log4rs
* Disable logging level filtering in Root logger
* Support different logging levels for file and stdout
* Don't log messages from modules other than Grin-related
* Fix formatting
* Place backed up compressed log copies into log file directory
* Increase default log file size to 16 MiB
* Add comment to config file on log_max_size option

p2p/src/msg.rs

@@ -26,7 +26,6 @@ use core::pow::Difficulty;
 use core::ser::{self, Readable, Reader, Writeable, Writer};
 
 use types::{Capabilities, Error, ReasonForBan, MAX_BLOCK_HEADERS, MAX_LOCATORS, MAX_PEER_ADDRS};
-use util::LOGGER;
 
 /// Current latest version of the protocol
 pub const PROTOCOL_VERSION: u32 = 1;
@@ -207,8 +206,8 @@ pub fn read_header(conn: &mut TcpStream, msg_type: Option<Type>) -> Result<MsgHe
 	// TODO 4x the limits for now to leave ourselves space to change things
 	if header.msg_len > max_len * 4 {
 		error!(
-			LOGGER,
-			"Too large read {}, had {}, wanted {}.", header.msg_type as u8, max_len, header.msg_len
+			"Too large read {}, had {}, wanted {}.",
+			header.msg_type as u8, max_len, header.msg_len
 		);
 		return Err(Error::Serialization(ser::Error::TooLargeReadErr));
 	}