Replaced CardConv with shscript, updated makefile

Deleted cardconverter and duplicated functionality in asy-gen.sh
Modified purple color in setcards.asy for disambiguation with red
Updated makefile rules to update images upon changes to setcards.asy, tracked by
image-stamp
Removed obsolete files from gui/ folder

Removed cardconverter, setcards.asy, setcards.java from gui folder due to
obselescence