Clean up steady state file examples/NK_baseline_steadystate.m to make it Dynare 4 compatible.

Also shows how to use file to impose restrictions using the check indicator
Add example3 that uses steady_state_model block to call fsolve
Add example files to manuals and describe what they do
Merge pull request #548 from JohannesPfeifer/master

Clean up steady state file examples/NK_baseline_steadystate.m to make it...