Current version passes:
    1-23
Current version fails on these tests because:
    none
Tests:
    1		initializations and to_s
    2		basic integer arithmetics and coertion to Z
    3		integer logical operators
    4		comparisions between Z, Q, FixNum and BigNum
    5		basic rational arithmetics and coertion to Q
    6		bit operations, scan0, scan1
    7		exponentiation and exponentiation modulo
    8		divide by zero exceptions
    9		sgn, neg, abs
    10		fibonacci, factorial, nextprime
    11		swap
    12		floor, ceil, truncate
    13		to_i, to_d
    14		shifts, last_bits
    15		logical tests, roots
    16	        floating point init with and without explicit precision
    17		basic floating point arithmetics and coercion to F
    18		default_prec and default_prec=
    19		integer division methods
    20		mpfr - exp and log
    21		mpfr - trigonometry
    22		mpfr - type tests
    23		mpfr - sqrt and power
TODO:
		jacobi, legendre, remove
		gcd, lcm
		cmpabs
		integer and integer->rational division, modulo
		more number theoretic functions
		random numbers
		range error exceptions
		others ?
