fixed: Big::Add incorrectly rounded 'this' when both exponents were equal
it caused that sometimes when adding a zero the result has changed
this had impact among other things on FromString() method
"0,8" had different binary representation from "0,80"
changed: renamed: Big::PowUInt(UInt<pow_size> pow) -> Big::Pow(UInt<pow_size> pow)
it returns 2 when there is: 0^0
changed: renamed: Big::PowInt(Int<pow_size> pow) -> Big::Pow(Int<pow_size> pow)
it returns 2 when there is: 0^0 or 0^(-something)
changed: renamed: Big::PowBUInt() -> PowUInt(), Big::PowBInt() -> Big::PowInt()
they return 2 when the arguments are incorrect (like above)
changed: UInt::SetBitInWord(uint & value, uint bit) is taking the first argument by a reference now,
the specific bit is set in the 'value' and the method returns the last state of the bit (zero or one)
added: UInt::GetBit(uint bit_index) - returning the state of the specific bit
changed: UInt::SetBit(uint bit_index) - it's using TTMATH_ASSERT now
changed: Big::Mod2() - it's using mantissa.GetBit() now
added: Big::operator=(double) and Big::Big(double)
added: TTMATH_ASSERT somewhere in ttmathuint64.h
added: UInt::Pow(UInt<value_size> pow) and Int::Pow(Int<value_size> pow)
git-svn-id: svn://ttmath.org/publicrep/ttmath/trunk@104 e52654a7-88a9-db11-a3e9-0013d4bc506e