bug
newton minimization - not much improvement, init guess is a problem
some work on global solver
work on global solver; compiles OK not tested!
work on Problem, Test, Seeder for tests
finished Problem, tested Problem, Seeder. fixed_dofs --> std::set
Test mechanism almost finished
Merge branch 'experimental'

Conflicts:
	eikonal/ls/ls_minimize.cpp
	eikonal/ls/ls_minimize.h