Fix propagation of modifiers in new instantiation

[Per Östlund]

The propagation of modifications in the new instantiation doesn't work in cases like this:

model A
  Real x;
end A;

model B
  extends A;
  Real x;
end B;

model C
  extends B(x = 5);
end C;

The propagation of modifications to elements is also very inefficient, and should be rewritten to use e.g. a hashtable or something.

[Per Östlund]

Fixed in r14429.

[Dietmar Winkler]

It doesn't make sense to keep closed ticket in the "Future" milestone that were simply forgotten to assign to the correct milestone in the past.

[Martin Sjölund]

Removing the pre1.9.4 milestone in favor of 1.9.4.