Remove old data-flow code from PLS_v1.

The code could build up a statically type checked data-flow graph without memory allocation.
It might be worth wile to bring the code back in future iterations, however, for now it does not work and clutters up the project.
3 jobs from master in 4 minutes 43 seconds (queued for 2 seconds)
Status Job ID Name Coverage
  Build
passed #4033
build_cmake

01:09

 
  Test
passed #4034
run_tests

01:09

 
  Sanitizer
passed #4035
run_address_sanitizer

02:24