Remove default head size from .bat, and added config option GH-5

dvb.bat

@@ -1,2 +1,13 @@
+:: leave JVM_FLAGS empty to let java determine heap size (depends on java version and machine memory).
+:: When you get an out of memory error (when parsing PES pids, or with large DSM-CC carrousels) you can use -Xmx to increase maximum heap size. 
+:: Use -Xms to set initial Java heap size. This can also help performance for large files. Suggestion try something like 
 
-java -classpath .;.\lib\jfreechart-1.5.0.jar;.\lib\opencsv-5.1.jar;.\lib\jlayer-1.0.1.4.jar;.\lib\commons-text-1.8.jar;.\lib\commons-logging-1.2.jar;.\lib\commons-lang3-3.9.jar;.\lib\commons-collections4-4.4.jar;.\lib\commons-collections-3.2.2.jar;.\lib\commons-beanutils-1.9.4.jar;.\DVBinspector.jar -Xmx1000m -Djava.util.logging.config.file=src/main/resources/logging.properties nl.digitalekabeltelevisie.main.DVBinspector
+set JVM_FLAGS=
+
+:: uncomment next line to set maximum head size to 1000 MByte
+::set JVM_FLAGS=-Xmx1000m
+
+:: uncomment next line to set initial and maximum head size to 4 GByte
+::set JVM_FLAGS=-Xmx48g -Xms48g
+
+java -classpath .;.\lib\jfreechart-1.5.0.jar;.\lib\opencsv-5.1.jar;.\lib\jlayer-1.0.1.4.jar;.\lib\commons-text-1.8.jar;.\lib\commons-logging-1.2.jar;.\lib\commons-lang3-3.9.jar;.\lib\commons-collections4-4.4.jar;.\lib\commons-collections-3.2.2.jar;.\lib\commons-beanutils-1.9.4.jar;.\DVBinspector.jar %JVM_FLAGS% -Djava.util.logging.config.file=src/main/resources/logging.properties nl.digitalekabeltelevisie.main.DVBinspector