removed old code related to user defined selection of hypothesis for disprover
as the disprover loads the complete event-b model anyway, the useContexts flag became obsolete. removed dead code.
remove some more dead code
delete obsolete file
remove obsolete exception, can not be thrown anymore
remove old load command, we now load the model directly
further refactoring: move fetching hypothesis from rodin directly into the reasoner.
remove obsolete preferences
remove old comments
remove unused local variable, simplifies constructor
return a reasoner failure instead of modifying the proof tree if a timeout occurs
remove old code