add ListVariables.bas by sorchard

http://archive.worldofdragon.org/phpBB3/viewtopic.php?f=5&t=4923&p=11649#p11649
Works also with CoCo ROM ;)
add original Hex Viewer script from:

https://github.com/jedie/PyDragon32/tree/master/HexViewer
renumber hex_view01.bas
enhanced the hex viewer program
add CoCo info to README