remove solver related feature of TriangleContourBuilder and split MarchingTriangleContourBuilder into nested classes
add ConstraintImplicitFunctionSolver interface
let MMAFunctionSolver implements ConstraintImplicitFunctionSover
remove trivial useless fields of MMSFunctionSolver
fix a bug caused by 630c4105c of TrackContourBuilderTest
extract genLinearInterpolateParameter() in AbstractTriangleContourBuilder
add MarchingTriangleContourBuilder.OnEdgeGradient
redesign TriangleContourBuilderDemo, fix broken condition since 630c4105c