Rigid testing - Division by Zero and more

Hi Dave,

I've made my first edits and fixed some bugs


      * Fixed CPAN RT bug #85332 Changes is 0 bytes (this file)
    
      * Fixed CPAN RT bug #87221 Division by Zero
    
      * t/15_zeroes.t: Added tests for divisions by zero
    
      * t/16_decimals.t: Added tests for unsupported non-integer arguments