IEEE-754 Based Floating Point ALU

Modules:

1. int2float: integer to float conversion
2. float2int: float to integer conversion
3. fadd_sub: floating point addition and subtraction
4. p_fadd_sub: pipelined floating point addition and subtraction
5. fmul: floating point multiplication

To Do

1. fdiv: floating point division
2. pipelined multiplication, division modules