fix(FestivalActivity): compare class of object with current class

Method "equals" compares class of objects that are being compared with
each other instead of static comparison
feat(FallEvent): add equals method, constructors, and setEventNum
feat(ast01-PartB): add professors code and example input file
feat(FallEvent): add method toString

Method toString prints FallEvent, it shows category as full category
name instead of category code
feat(FestivalActivity): change toString method output
feat(FallEvent): add default clause for switch statement
feat(FallFlavours): add file parser

Added constructor for FallFlavours class that parses file and stores all
its content in vault