Added Xapian::TfIdfWeight to the Registry.
Added TfIdfWeight to csharp makefile.
Added TfIdfWeight to the java makefile.
Merge pull request #2 from ojwb/tfidf

Tfidf whitespace-related fixes
Fix ChangeLog formatting
Move TfIdfWeight constructor out of the header to avoid needing <cstring> there
Fix parameter name to match doxygen @param
Fix documentation typos
Add whitespace around binary operators