resample should use `similar`

[ssfrr]

Currently resample always returns an Array even if the input was some other AbstractArray. It should use similar so that the returned value is the same type as the input.

MWE:

julia> using SampledSignals, DSP

julia> buf = SampleBuf(rand(100), 48000)
100-frame, 1-channel SampleBuf{Float64, 1}
0.0020833333333333333s sampled at 48000.0Hz
▇▇▇▆▆▇▇▆▇▇▇▆▇▇▇▇▇▆▇▆▇▆▇▇▇▆▆▇▇▆▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▆▆

julia> resample(buf, 1.2)
120-element Array{Float64,1}:
 0.8790735553966081
 1.0707055066803346
 0.5417156513066438
 0.9083973585054169
 ⋮
 0.0819987776177565
 0.3151630859175723
 0.16424615564476444
 0.17496872135247912

[jfsantos]

I'm guessing that's because of this line?

[martinholters]

Yes, that should probably be

buffer = similar(x, promote_type(Th,Tx), bufLen)