Generates report and implement most of pretty printer functions

[julianayang777]

• New: Generates a json file report.json that contains some execution metrics and counter models that were found during the execution.
• Implemented pretty printer functions with the layout that it has in the to string functions for modules (Implement the remaining pretty printers for all the modules #13). The only module that does not have pretty printer functions implemented is HeapTree.ml.
• Rename the entry point function from aenima to main
• Rename the module PathCondition to PC
• Grouped heap modules in the directory Heap