Fix bug with the Children dictionary removing the original values during the clone operation
Fix texture axes becoming corrupt when copying brushes. Fixes #93, fixes #133.

This issue was caused by the CurrentCulture being used to print a texture axis, but the InvariantCulture is used to parse it.
If the current culture uses comma as a decimal separator, parsing the texture axis will fail. If parsing fails, the VMF provider defaults to UnitX.