Add simple Cython optimizations

Adding static types of variables speeds up things about 3 or 4 times.
This is enough for the time being.

Signed-off-by: Ignas Anikevicius (gns_ank) <anikevicius@gmail.com>
Add more realistic data modelling

Now each pulsar is timed for several times and the schedule of pulsar
observations is independent, which means, that we have more realistic
way of generating the data.

What I could do now is to speed up whilst generalising the data
generating bits into Cython.

Signed-off-by: Ignas Anikevicius (gns_ank) <anikevicius@gmail.com>