Switched the 'pragma once' to only happen on MSVC, or gcc >= 3.4 (it was causing trouble on the sun compiler)

Marked Parser, Emitter, Node, Iterator, Mark, and Null for exporting to a DLL. It appears to work properly, although VS gives me lots of warning C4251 since I didn't export all data members of each of the above classes.

It seems that it's not necessary to export those members (as long as you can't access them), and most of them are STL instances, which apparently cause lots of problems for DLLs. (For example, you simply can't export instances of std::map; see http://support.microsoft.com/kb/168958.)

Removed comparison/implicit conversion operators for Node, and renamed Node::Read<T>() to Node::to<T>()

Fixed folding bug (detecting indentation, example 8.2), and clipping/stripping empty strings (example 8.6)

Refactored parse.cpp so that VS doesn't complain, added MinSizeRel build setting, and fixed numbering in the spec tests

Added explicit doc start/end tokens for the emitter, and set it so that if you try to write after you've already written a full doc, it writes a doc start and continues