Simplify a big rational .

Prototype
   int BigRat.simplify( brat )

Parameters
   brat
      Rational to be simplified.

Remarks
   brat must be created before function call

Example
   
require( "BigRat.lua" )

a = BigRat.new( "600", "225" )
BigRat.simplify( a )
print( a )

b = BigRat.new( "-540", "99" )
BigRat.simplify( b )
print( b )

--Try to simplify a non valid parameter
ret = BigRat.simplify(  )
print( ret ) ;
   
Output
   
8/3
-60/11
0