perf: Improve Tektronix_AWG5014 performance

[antsr]

pack_waveform in Tektronix_AWG5014 uses Python native functions like min, max and count,
which are slow compared to the numpy alternatives. This update replaces the Python function calls
with numpy alternatives considerably improving the speed of programming the Tektronix AWG5014
while leaving the functionality the same.

As an example, on my machine:

> data = np.random.choice([0, 1], 10000)

> %timeit list(data).count(0) + list(data).count(1) == len(data)
100 loops, best of 3: 5.23 ms per loop

> %timeit np.all(np.in1d(data, np.array([0, 1])))
The slowest run took 9.76 times longer than the fastest. This could mean that an intermediate result is being cached.
10000 loops, best of 3: 70.3 µs per loop

Changes proposed in this pull request:

• Change native Python functions in Tektronix_AWG5014.pack_waveform to numpy versions.

@giulioungaretti

[WilliamHPNielsen]

That is indeed a change that is only an improvement. Good job.