Update cool.flex

this version updates the correct version for comments
the comments now do not include EOF 

also some special characters have been added

rule for strings have been removed as it was incorrect
strings have  to be adaptive for multiple backslashes 
all characters except {b,n,f,t} have to be treated as characters while {b,n,f,t} are string manipulaters(eg. newline backslash tab etc)