Association-measures

compatibility release
- drop support for `Python3.8` (reached EOL), support `Python3.13` instead
- switch from `pipenv` to `venv`
- use `pandas` >=2.2.2 and `numpy` >=2.0 (`numpy2` and `pandas2` are now compatible again)
- include separate `requirements-dev`
- remove `travis.yml` (everything runs in GitHub actions anyway)

also includes some WIP on categorisation of measures and profile comparisons

- add feature for creating topographic grids
- default to Poisson boundary in LRC
- now requires Python>=3.8, pandas>=2.0

- discounting according to Walter1975 for log-ratio
- make Poisson boundary the default for LRC
- major performance improvement for LRC with Poisson boundary
- further performance improvement: only calculate scores once for each frequency signature

- force np.vectorize to return float, otherwise conservative log ratio might be rounded to integer

- repair measuring performance
- do not calculate binomial likelihood by default

make calculation of conservative log ratio with Poisson boundary robust against observations with O11=O21=0: return 0.