[pdal] dimension_types branch merge

[Howard Butler]

Michael,

I have merged my dimension_types work back into the main branch.  I suspect that I broke all of the SWIG-based stuff in the process, as I didn't make any updates to sync that with the effort.

All tests currently passing on my Snow Leopard system, but on my Lion system with boost 1.47, I get the following error:

> [  1%] Building CXX object src/CMakeFiles/pdal.dir/plang/AstUtils.cpp.o
> /Users/hobu/dev/git/pdal/src/plang/AstUtils.cpp: In static member function 'static pdal::plang::DataType pdal::plang::AstUtils::inferType(pdal::plang::variant_t)':
> /Users/hobu/dev/git/pdal/src/plang/AstUtils.cpp:62: error: no matching function for call to 'apply_visitor(pdal::plang::AstUtils::inferType(pdal::plang::variant_t)::my_visitor, pdal::plang::variant_t&)'

The long and the short of my dimension_types work up to this point is that PointBuffer::getField and setField now require a Dimension const& *from the PointBuffer's Schema* to do their business. We no longer operate based on explicit dimension positions (this is now managed by the Schema for the Dimension). The other items I was discussing are partially complete, but I reached a point where continuing to keep things up to date with the master branch was going to get quite hairy.

I will continue development on the master branch to implement the removal of Stage::getSchema and friends. Hopefully this work will be done by the end of the year.

Howard