Proposed resolution of non-unique IDs in GMSH format.
Add solving of non-unique IDs in GMSH format.

- add multi index member only for region IDs to RegionDB
- add exceptions for non-unique region IDs
- create RegionDB::find method for search by ID parameter
- small optimizations of RegionDB class (naming of types, method etc)
Modify of exception of non-unique region.

- use only input exception
Modify RegionDB::add_region method.

- remove check dimension consistency
- add code for adding region with undefined dimension
Finish of implementation of nonunique region id.

- fix error in add_region method
- add unit test
Optimization of RegionDB::add_region methods.

- create separate private methods for insert region, update dimension
and testing of existing region.
- use these methods in add_region methods
Fix error in RegionDB.
Remove boundary parameter in add_region method.
Fix error in insert implicit boundary region.
Merge branch '1.8.0_master' into DF_nonunique_id
Merge branch 'DF_nonunique_id' into 1.8.0_master
Change publish dir for doxygen doc.

- rename from 'source_doc' to 'doxygen'
  which is conforming with older releases
Replace 3-dim array of concentration in convection transport with only 2-dim array.
Deal with no sorbing surface in sorption (porosity equal one).

- if porosity close to 1 in machine precision then set sorption none
- improve user error messages
- add sorption term in test 15 (where porosity is 1) so the results are unchanged due to this fix
Merge branch '1.8.0_master' into PE_reactions

Conflicts:
	src/transport/transport_operator_splitting.cc
Add example for using EI_Address.
Merge branch '1.8.0_master' of github.com:flow123d/flow123d into 1.8.0_master
Introduce RadioactiveDecayProduct record.
Introduce exceptions in reading substances names in reactions.
Clear namespace of armadillo in reactions.