Move MockSocket to util package

It's not only used for tests.
make Slimtable child tables a linked list
Moved test summary counts to contexts.
Merge branch 'slim_refactoring' of github.com:barredijkstra/fitnesse into slim_refactoring
Moved all system configuration to Descriptor class
Fixed class path generation again by moving all classpath stuff to the ClassPathBuilder
Extend Instructions with functionality needed on client
swuash with instructions
Use Instruction on client side. Changes all over the place!

Huge commit!