Jenkins builds, keep going when make unit tests.

- run through all targets, do not stop on the first error
Fix unit tests in release builds.

- minor modifications in tokenizer_test.cpp, field_base_test.cpp, type_base.cpp
  to fix death tests
- introduce EXPECT_ASSERT_DEATH macro to test important assertions which however
  should not be tested if compiled without DEBUG_ASSERTS
- move all our extensions into _gtest_extensions subdirectory
- unit tests should include just flow_gtest.hh or flow_gtest_mpi.hh
- allow to switch off all death tests using preprocessor macro:
  UNIT_TESTS_NO_DEATH_TESTS
  .. usefull to run death test under valgrind, not yet incorporated
  into CMakeFile.txt
Fix bug - segmentation fault in test 12.

- petsc seg. fault in transport, compute_one_step
- solution: pointers to sorption, decay, semchem etc. intialized in TOS constructor
Merge branch 'master' of https://github.com/flow123d/flow123d
Second try to fix release build.

- seems that gcc 4.4.7 have bug in clone() function or at least is incompatible with
  gtest, so we switch to unsafe version of death tests this however may produce different errors
Merge branch 'master' of https://github.com/flow123d/flow123d
Fix part of pullrequest #83 up to darcy_flow_mh.

Minor changes and cleanup work.
Removed BDDCML_CDEFS, that was added to linking of lib_la.
Fixed DarcyFlowMH_Steady destructor.

- hopefully no more memory leaks
Minor fixes.

       modified:   src/flow/darcy_flow_mh.hh
removed unnecessary mdata members
       modified:   src/flow/darcy_flow_mh_output.cc
fixed potential problem opening files on all processors
       modified:   src/la/linsys.hh
removed unnecessary petsc header
       modified:   src/la/linsys_PETSC.cc
inclued requerd petsc headers
       modified:   unit_tests/la/CMakeLists.txt
rename of schur unit test
Merge branch 'master' into trunk_1.8

Conflicts:
	unit_tests/la/inversion_matrix_test.cpp