Float arithmetic and comparison tests
Float square root. MPIR 2.7.0 section 7.5 completed.
updated XML comments for comparisons with a double
Float Equals (approximately), RelativeDifferenceFrom.  MPIR 2.7.0 Section 7.6 Completed.
Moved float arithmetic and comparison tests to the correct location.
Float construction and disposal tests.
Float Changing precision.  MPIR 2.7.0 section 7.1 completed.
Float assignment tests.
Float conversion tests and full implementation of ToString()
Float expression tests