libtensorflow_1_15_0: init at 1.15.0

Also bring back libtensorflow 1.14.0. It's nice to have prebuilt
Tensorflow versions available with optimizations and multiple CUDA
capabilities. So, let's add them back to my package set.
python3Packages.somajo: 1.10.5 -> 1.10.7

Changelog:
https://github.com/tsproisl/SoMaJo/releases/tag/v1.10.6
https://github.com/tsproisl/SoMaJo/releases/tag/v1.10.7
alpino-tokenize: init at 0.1.0
python3Packages.alpino-tokenizer: fetch source from sr.ht
python3Packages.alpino-tokenizer: init at 0.1.0
CI: update to nixpkgs 19.09

NixOS 19.09 does not seem to be available on builds.sr.ht yet.
Remove sticker packages

All sticker-related packages have been moved to:

https://github.com/stickeritis/nix-packages
ci: get the list of buildable packages automatically

This uses the (modified) ci.nix file from the NUR template:
https://github.com/nix-community/nur-packages-template/blob/master/ci.nix
Remove finalfusion packages

All finalfusion-related packages have been moved to:

https://github.com/finalfusion/nix-packages
alpino: cleanup
fsa6: make derivation more canonical
dact: reuse pname/version, add maintainer
alpinocorpus: version is already a string
alpinocorpus: 2.8.3 -> 2.8.4
dact: 2.6.6 -> 2.6.7
stickerModels.de-ner-ud: init at 20190825
stickerModels.de-deps-ud: 20190821 -> 20190823

This model improves LAS with better hyperparameters.
stickerModels: update for sticker 0.6 configuration changes

The models have not been changed otherwise.
sticker: 0.5.0 -> 0.6.1
CI: don't create package set, build in-place
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