[svn r112] Fixed 'case 1,2,3:' style case statements. Fixed a bunch of bugs with return/break/continue in loops. Fixed support for the DMDFE hidden implicit return value variable. This can be needed for some foreach statements where the loop body is converted to a nested delegate, but also possibly returns from the function. Added std.math to phobos. Added AA runtime support code, done ground work for implementing AAs. Several other bugfixes.

module bug6;
class wrong { }
void bark(ref wrong s) { s = new wrong; }
void foo(wrong tree) {
    auto old = tree;
    bark(tree);
    assert(old !is tree);
}
void main()
{
    auto w = new wrong;
    auto old = w;
    foo(w);
    assert(w is old);
}