1.394 - maintenance

- added data(Dissertations) with its man page
- improved numerical stability of dlaplace
- fixed rlaplace to actually work correctly
- added dgnorm, generalized normal type 1 density
- various plotting functions now set narrow margins automatically via
set_nice_margins()
- map2stan uses new vectorized multi_normal syntax for built Stan code,
making sampling substantially faster in some cases
- fixed bug with precis mixing up matrix parameters in ordering. Now
uses postlistprecis() internally to get things right.