Changes regarding *home-directory* variable and the Primitives.open function

1)*home-directory* was being overwritten during the loading of the declarations.kl file. As a result intern("*home-directory*").value() was returning an empty string upon a call of the "load" function (after the declarations.kl file had been loaded). This meant that in order to "load" a file the absolute path was required.

Changed the code so that *home-directory* points to the home directory even after loading of the declarations.kl.

2)Made changes to Primitives.open function so that it detects whether one is specifying absolute path or not, and appropriately handles each case.