Fix TransportDG.

- fix setting size of arma::vec vectors
- set longer time limit for unit tests
Fixed field flags for some quantities in transport equations that affect re-assembling stiffness matrix and r.h.s.
Update README pointing to main web page.
Merge branch '1.8.0_master' of github.com:flow123d/flow123d into 1.8.0_master
Merge branch '1.8.0_master'

Conflicts:
	README.md