Added customizable command log format (Date+Time are now available)

Added the option format to config files (config.yml + worldedit.properties). By default, current date and time are displayed.
The formatting function is implemented by analogy with the class java.util.logging.SimpleFormatter

worldedit-forge/src/main/resources/defaults/worldedit.properties

@@ -18,6 +18,7 @@ scripting-timeout=3000
 snapshots-dir=
 use-inventory-creative-override=false
 log-file=worldedit.log
+log-format=[%1$tY-%1$tm-%1$td %1$tH:%1$tM:%1$tS %4$s]: %5$s%6$s%n
 max-changed-blocks=-1
 nav-wand-distance=50
 butcher-default-radius=-1