Bugfixes, documentation, and features

- Further corrections related to #316 (consistent naming of fields)
- Closes issue #315 (saving of MCMC chain info into oo_)
- Adds warning and information for #278 (first order variance decomposition at order 2)
- Adds endogenous prior option of Christiano/Trabandt/Walentin (2011)
- Adds missing option in identification
- Makes some graph titles more expressive
- Bugfix for rplot