Cmake build: modify some tests

Cmake build: modify some tests

a) test export/templates/ectaart_pdf5 removed, because
    of incompatibility between ectart.cls and luatex.sty
b) renamed some tests to reflect their purpose
    tex2lyx2lyx/roundtrip/ => tex2lyx/cmplyx/
          # the tests are comparing files written by lyx (not by tex2lyx)
    autotests/ => keytest/
          # we are testing reactions of lyx to some key strokes
c) add tests for lyx2lyx. This is rather rudimental, in that it only
    checks for created output, error codes and error output.
d) use correct environment variable to set up the userdir for testing