* CaseInsensitiveHashCodeProvider.cs: In default ctor, do not save

* CaseInsensitiveHashCodeProvider.cs: In default ctor, do not save
TextInfo if current culture is invariant. Remoted private ctor.
In Default, always construct new instance since the current culture
may change.
* CaseInsensitiveHashCodeProviderTest.cs: Improved test for
Default property to show the a new intance is constructed. Added test
for DefaultInvariant. Improved serialization tests. Added ctor test
for null CultureInfo. Code formatting.
* CultureInfoTest.cs: Fixed UseUserOverride tests to pass on systems
where invariant culture is default locale.

svn path=/trunk/mcs/; revision=81408