Merge remote-tracking branch 'origin/master' into JSI_bddc

Conflicts:
	src/flow/darcy_flow_mh.cc
Merge branch 'JSI_bddc' of github.com:flow123d/flow123d into JSI_bddc
Fix system.hh for case without HAVE_PETSC
Replace get_field by operator[].

- overload operator[] (returns reference, and throws for unknown name)
- field() method returns pointer (nullptr if not found)
Merge branch 'master' of github.com:flow123d/flow123d into JSI_bddc
assemble diagonal weights in BDDC

- instead of creating a map with the weights, register them in the
  linsys and then assemble this matrix for loading to BDDCML
Analytical solution for transport problems.

- preliminary text incorporated into documentation
Distinguish field "name" and "input_name".

- introduce Field<..>::name attribute which identifies
  the field in a FieldSet
- distinguish this from input_name used to declare and read appropriate key
  in the input filed descriptor
- introduce methon input_name() to read the input_name
- rename setters used just for input
- fix unit tests
Merge remote-tracking branch 'origin/JSI_bddc'
Merge branch 'master' into 1.8.0_master
Merge branch '1.8.0_master' into JB_finish_fieldset
Small fix in BIH tree.
Fix test 22 under Cygwin.

- add using of Python under Cygwin
Temporary fix for wrong ASSERT.
Introduce FlagArray.

- bitfield like class that allows setting and testing
  arbitrary subset of bits.
Introduce FieldFlag class.

- this class just defines FlagArray type used by Field classes
  and common Masks to set and test
- in order to make these masks easily accesible from FieldSet, we make
   FieldSet descendant of FieldFlag
- add FieldCommonBase::flags() getter
Replace FieldCommonBase::just_copy() method

- remove the method, remove is_copy member
- replace it by flag declare_input turned off
- introduce mask input_copy to this end
- add constructor of FlagArray from a Mask
Fix missing include.

- add missing conditional include of petsc.hh
correct name of the member function
Fix memory leak in LinSys_PETSC::gatherSolution

- need not to call VecCreateSequential, vector created by VecScatterToAll
- improve bin/valgrind.sh, allows passing additional parameters to valgrind

close #112