Attempt to dereference null GDALProgressFunc error in SWIG C#

[tamas]

The method Dataset.BuildOverviews?(string resampling, int[] overviewlist) generates the exception: "Attempt to dereference null GDALProgressFunc".

It seems the recently added callback support have broken some of the existing functions at the SWIG C# interface. In order to make this callback stuff work some typemaps should also be added that I've originally planned to implement later. But as looking into the code since the problem is critical and it seems quite an easy to implement this, I'll commit a fix in the SVN trunk and the branch 5.0

[tamas]

Applied the fix in trunk and branch 1-5 (r13458 , r13459)

[tamas]

Closing upon positive user feedback