Apertium Turkic/Use/MT

The dictionary languages/apertium-kaz/apertium-kaz.kaz.lexc has a bunch of lines with the comment ! Use/MT eng-kaz. These lines are only to appear in machine translation pairs, not when creating a "vanilla" transducer. It's easy to grep them out, but harder to get this into the current build system where language pairs depend on the pre-built att.gz of languages/apertium-kaz and trim that.

Some options:

1. Make two binaries in languages/apertium-kaz, one vanilla and one MT.
   • Cons: Takes a lot longer to make apertium-kaz
   • Installed size of languages module doubles
   • Messy
2. Make two transducers in /languages/ (vanilla + MT), but run the MT only to att.gz, while the vanilla is run to full binary.
   • Cons: Takes longer to make apertium-kaz
   • Installed size of languages module increases
   • Still a bit messy
3. Have Use/MT as a visible tag, with paths (vanilla) or tags (MT) removed by postprocessing scripts (or CG)
   • Cons: Ugggly
   • Ugly
   • Ugly
4. Have Use/MT as a compiler-tag, paths with this tag are removed by twol when compiling for vanilla, while the tag itself is removed by twol when compiling for MT
   • Cons: compilation-internal tags, that's almost as bad as flag diacritics.
5. Redundant make steps in pairs: the pair references $(AP_SRC1)/apertium-kaz.lexc and does all the same steps up to att.gz which are specified in the /languages/apertium-kaz/Makefile (except in /languages/, there's a "grep -v Use/MT" line in the lexc-step)
   • Cons: Lots of redundant make code
   • An update one place leads to a lot of Makefiles having to be updated
   • It takes a lot longer to make each language pair
   • Messy
6. Create a binary transducer with only the "grep Use/MT" lines. Use "hfst-subtract MT.bin Use/MT-only.bin" to subtract only the Use/MT lines from the MT transducer to create the vanilla transducer in /languages/
   • Cons: We can't simply "grep Use/MT *lexc", since we also need the LEXICON lines and dog knows what else
   • It would lead to really ugly lexicon-specific rules
   • We still end up with two binary transducers in /languages/
   • Ugly
7. Use a ./configure option (e.g. --with-variant=mt, --with-variant=vanilla) to switch a particular checkout of apertium-kaz to do one or the other (basically just ifdef some greps in the makefile).
   • Cons: Means that if you want both you need two checkouts, or keep switching back-and-forth.
   • Easy to forget which version you have, and not know why your MT pair suddenly doesn't work like it should
     • That can be counteracted a bit by having the make goals give them different names