optional Directory Reference

Directories
	gsCoDiPack
	gsElasticity
	gsHLBFGS
	gsIpOpt
	gsKLShell
	gsModule
	gsMultiPrecision
	gsOpenCascade
	gsOpennurbs
	gsOptim
	gsParasolid
	gsPolynomial
	gsSpectra
	gsStructuralAnalysis
	gsTrilinos
	gsUnitTest
	gsUniversal
	gsUnstructuredSplines
	gsXBraid