* Addressed issues brought up in Chris's review of Morgan's

* Addressed issues brought up in Chris's review of Morgan's
  NodeManager (bug #65).  Better documentation, etc.

* As part of this, removed NodeManager::mkVar() (which created a
  variable of unknown type).  This requires changes to lots of unit
  tests, which were using this function.

* Performed some review of parser code (my code review #73).

  + I changed the way exceptions were caught and rethrown in
    src/parser/input.cpp.

  + ParserExceptions weren't being properly constructed (d_line and
    d_column weren't intiialized and could contain junk, leading to
    weird error messages).  Fixed.

* Fix to the current working directory used by run_regression script.
  Makes exceptional output easier to match against (in expected error
  output).

* (configure.ac) Ensure that CFLAGS has -fexceptions in it, in case we
  compile any C code and don't use the C++ compiler.