#12 Test path to rt.jar in injectj.ini at startup

[Uwe Freese]

After installing a new Java version, I didn't recognize that
the path to my rt.jar was now wrong in injectj.ini.

Inject/J should check the paths in the INI at startup and
output an error message if a file doesn't exist ("File ...
doesn't exist. Please check your ini file in d:\Eigene
Dateien\injectj.ini"). It should tell where the ini file is.