Cleaned up tridiag test.
Fix #119

- Cleaned of the eigensystems computations (worker is simpler, decision
  at runtime, etc..).
- Fix #119 : When the matrix is in C order, the fortran lapack
  sees in fact its conjugate, so we need to conjugate the eigenvectors at the end.
  NB : not true if the storage order of the matrix is already fortran of course.
Clean the eigenelements tests.

- Clean the output of the test.
- Separate from previous commit to be able to retest previous test
  with same lib code.
Merge branch '1.2-dev' of github.com:TRIQS/triqs into 1.2-dev
Slight coding style impovement in tridiag_worker
Merge branch 'complex_tridiag' into 1.2-dev