Update doc of flow123d.sh

- also minor fix in help of flow123d.sh
Resue old test 09
Reuse test 09 for time dependent steady flow

- new test
- not implemented yet
Input::Type::Record permissive auto conversion

- auto conversion allowed also for records with optional and at_read_time
  keys; we disallow only obligatory keys without default value
- Fix placement of INPUT_EXCEPTION declaration
- avoid redefinition of ASSERT_LE macro under gtest
- add missing check for correct default descendant of an abstract record
TimeMarks::last method

- last(mask) method fins last mark matching given mask
- restructuralization of sources
Fix logging.

- remove annoying DBGMSG from Profiler
Masked begin,end in TimeMarks

- optional mask parameter added to TimeMarks methos begin and end
Prepare TimeGovernor for generalized steady eq

- support for steady time stepping in estimate_dt
- simplify constructors
- move equation mark type from EquationBase into time governor
- less strict input record
- method: add_time_marks_grid - calls similar method of TimeMarks
  using known start and end time
- minor changes in equations to adopt change in equation mark type
- fixes in unit test