Revamped HGLET functions

Added HGLET_Analysis and HGLET_BestBasis functions in HGLET.jl for the user convenience. At the same time, many functions in HGLET.jl have been revamped and improved. Consequently, some input argument names (cfspec instead of method) and/or some statement (e.g., isnothing(A) rather than A == nothing) of several other functions in helpers.jl, LP-HGLET.jl, partition_fiedler.jl, unbalanced_haar_image.jl, common.jl, LP-NGWP.jl, GHWT.jl, GHWT_tf_1d.jl are modified.