adjusted default values in Job
Operation as flyweight - Jobshop as flyweight factory;
Jobs now id-ed by letters, operations by job-letter and number
Chromosome class (just scratch)
cleenups in Operation
horizontal header in tableview presents job id;
various fixes and cleanups
serialisation of Job class
fixed serialisation of Operation class
can now import jobshop problem silently
presentation realted fixes
Fixed import and export
Working generating initial population