Merge ASP and OMP tracers

[mpf]

Implement a push! method that replaces each of these 3 pushes with a single push:

ActiveSetPursuit.jl/src/BPDual.jl

Lines 370 to 382 in b602cef

	if traceFlag
	push!(tracer.iteration, itn)
	push!(tracer.lambda, λ)
	sparse_x_full = SparseVector(n, copy(active), copy(x))
	push!(tracer.solution, copy(sparse_x_full))
	end
	end
	push!(tracer.iteration, itn)
	push!(tracer.lambda, λ)
	sparse_x_full = SparseVector(n, copy(active), copy(x))
	push!(tracer.solution, copy(sparse_x_full))

Similarly for the OMP tracer.

You might even consider a single tracer object, since the only difference is the additional lambda field in the ASP tracer.