ir: Use mode_is_float()/mode_is_int() instead of get_mode_sort()/->sort == irms_float_number/irms_int_number.

There are still similar problems left.

* This corrects the requirements of fStore.

This properly models the data dependencies and avoids keep edges.

Determine the pos from the node to push.

This replaces several 1/0 and true/false by yes/no.

Many x87 nodes do not need the x87-specific attributes.