modification_tracker

Changes made in this branch which should be merged to Master:

  (1) Fixed pathcrawler's seemingly false constraints in traces
  - DESCRIPTION: The trace output from pathcrawler can have constraints in the `Path Predicate'
    section which are false. This is due to the floating point numbers not being printed to the
    precision equivalent to eclipse's internal representation.
  - SOLUTION: Assume any trivially False constraint to be True.
  - FILE: ./path_crawler_helpers/prep_trace.py
  - TAG: FP_TRUE

  (2) Added the support to initialize the matlab plant using Matlab's classes
  - DESCRIPTION: Matlab plant simulators had to call init() inside the sim() call to load_system().
    This is now supported by using classes, similar to Python simulators. Moreover, 
    the modifications are backwards compatible. psim.py uses internal logic to detect if the
    supplied matlab simulator file is a class or a function and takes appropriate actions. This is
    planned to be removed in the future. Should probably not merged with the main branch?
  - SOLUTION:
      -Added init_plant.m
      -Copied simulate_plant.m to simulate_plant_fun.m
      -simulate_plant.m was modified to work with classes. This adds the feature to call init()
  - FILE modified: ./psim.py, ./simulate_plant.m
  - TAG: CLSS

  (3) Added sanity checks in loadsystem.py,   
  - DESCRIPTION: Makes sure that all required parameters are present in the .tst file. Also ensures
    consistency by catching and reporting any dimensions mismatces.
  - SOLUTION:
      - Added try: except blocks and created an exception class to print user friendly erorr
        messages when an expected parameter is missing
      - parse() was replaced by a new parse() and saved as
        parse_without_sanity_checki())
      - Created a new class MissingSystemDefError
  - FILE modified: ./loadsystem.py
  - TAG: No tags, as changes were pure additions and replacements. NO EDITS

  (5) Z3 is required only if symex is explicitly requested
  - DESCRIPTION: Z3 no longer needs to be installed if -ss-symex is never provided.
  - SOLUTION:
      - smt_solver is imported only if its required.
      - Earlier, it was loaded in both plant and controller
        abstractions. Now, its loaded in abstraction and passed to the plant and the controller
        abstraction. If not required, then its inited with None.
  - FILES modified: PACell.py, CASymbolicPCrawler.py, abstraction.py
  - TAG: Z3_IND

  (6) pc_trace_parser.py is required only if symex is explicitly requested
  - DESCRIPTION: ./path_crawler_helpers is not required unless symex is requested
  - SOLUTION: Changed unconditional import of CSymLoader.py conditional
  - FILES modified: secam.py
  - TAG: PCH_IND

  (7) eps: do not splice
      Tried to accept inf in grid_eps, implying 'do not splice'.
      Changes are checked in the 'eps' local branch.
      TAG: EPS

  (8) Added the new R2015b feature to connect to an existing Matlab session.
      Can use the switch --meng 'session name'
  - TAG: MSH
  - FILES: secam.py, psim.py, loadsystem.py