Xcode files.
include/sparsehash added.
Merge branch 'dpj-dev' of github.com:deltadev/sga into dpj-dev

Conflicts:
	sga.xcworkspace/contents.xcworkspacedata
	sga.xcworkspace/xcshareddata/sga.xccheckout
	sga/sga.xcodeproj/project.pbxproj
Fixed sparse hash headers.
Added option to preprocess to keep rejected samples.
Xcode settings.