minus sign

- there should be "-" sign in -C - B(A^-1)B in generation of interface
weights for BDDC
- this seems to improve convergence of BDDC for 1D-2D-3D cases
response to issue #92

Cleaning the interface to BDDCML.
A bug fixed in creating diagonals for interface weights for BDDC.
missing header
Optimization of BIH tree unit test.

- add test of find_point method
- add using of timer to test
- optimization of test class inner structure
Small change in unit test of BIH tree.

- add method for test of minimal, maximal and average depth.
BIH tree test of large mesh.

- add test of large mesh
- only geo file is stored in repository
Add printout of BIH tree structure.

- methods for print structure of nodes.
- add test of median, minimal and maximal count of elements in tree.
Fix of BIH tree construction.
Clean code of BIH tree.
Merge branch 'master' into DF_bih_tree
Merge tag 'release_1.8.0'
Merge branch 'master' of github.com:flow123d/flow123d into JSI_bddc

completed merge of master into JSi_BDDC

Conflicts:
	src/flow/darcy_flow_mh.cc
	src/la/linsys.hh
implemented missing routines for BDDC

mat_zero_entries
rhs_zero_entries

NODE macro avoided in bddcml_wrapper
added comments
update to BDDCML v 2.4
HOME variable
update CMake installation script

- download BDDCML 2.4
Merge remote-tracking branch 'origin/master' into JSI_bddc

Conflicts:
	src/flow/darcy_flow_mh.cc
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
Merge branch 'master' into 1.8.0_master