FPU v3 with the rounding mode

V4 of the FPU
I've add a test pannel. 
Only the rounding mode are missing.

FPU v3 
Gestion of infinite and flags (overflow, underflow ... ) 
Only Inexact operation and Invalid operation.

FPU v2 : 
Based on FPU v1, we now handle the subnormal float.

On this version all the operation instructions , except the square root, are supported. The Load and Store instruction are also supported.
For the moment only normal float are handle and no exceptions are raised.