Range_operator and range_operator_float are 2 different classes, which 
was not the original intent. This makes generalized dispatch to the 
appropriate function more difficult.  The distinction between what is a 
float operator and what is an integral operator also blurs when some 
methods have multiple types.  ie, casts : INT = FLOAT and FLOAT = INT, 
or other mixed operations like INT = FLOAT < FLOAT

This patch unifies all possible invocation patterns in one 
range_operator class. All the float operators now inherit from 
range_operator, and this allows the float table to use the general 
range_op_table class instead of re-implementing another kind of table.  
THis paves the way for the next patch which provides generalized 
dispatch for the various routines from a VRANGE.

There is little functional difference after this patch. Bootstraps on 
x86_64-pc-linux-gnu with no regressions.  Pushed.

Andrew