#358 Enhanced "System Properties"

[Mathias Ricken]

Since DrJava may now use ConcJUnit, an rt.jar file generated with ConcJUnit, OpenJDK or the Mint compiler, we should consider improving the information contained in the "System Properties" that we ask users to submit when they have a problem.

For example, if an external JUnit jar is used, we should report the date, file size and perhaps the contents of the manifest file. Same with the rt.jar file, if one is used.

We should log more information about the compilers that are scanned and used, and also report the date, file size, and manifest file of the tools.jar/classes.jar/Classes.jar file.