More fixes for the device independent jar

I fixed the batch file of the device-independent jar so it tried to find a JAVA using java variable or PATH. I could have added an "I am sure I have a java somewhere, find it" option, but I think most users would prefer DOWNLOADING java than waiting for five minutes for the batch file find an "autofirma" or "processing" or "Android Studio" installation that includes Java.

I have also found that the original version does not pass the first screen. I don't understand why, since I tested the processing PDE source before updating it (what I didn't test was the generated .exe, that's the reason why I uploaded a wrong .exe to the jam).

Next three weeks I will be preparing and cheking tests for my students of Spanish language. So don't expect much activity until April.