rational approximation using direct solvers added
Merge pull request #1203 from lambday/feature/log_determinant

rational approximation using direct solvers added
minor documentation fix in log-det framework
Merge pull request #1204 from lambday/feature/log_determinant

minor documentation fix in log-det framework
refactor evaluation of posterior and predictive distributions
Merge pull request #1206 from votjakovr/feature/gp_refactoring

refactor evaluation of posterior and predictive distributions