Update new adapt.delta default for Stan 2.1.0
Multiple improvements, require processManager 0.4+

StanModel
 - ENH: allow user-defined inits
 - BF: Better check for file existance when passing 'file', previous check
   was checking within Matlab path.
 - BF: 'algorithm' parameter works for 'hmc', which in CmdStan is 'static'
 - Remove manual Stan RNG incrementing. This is already handled by CmdStan
   using the 'id'.
 - BF: correctly empty binary checksum when new model is specified for an
   instance and the model does not exist, but did before

StanFit
 - Update processManager requirement (0.4+). This fixes lots of problems
   including repeated notifications
 - Attempts to access StanFit attributes that are not ready (eg. Stan is
   still sampling) now returns empty arrays and a more informative message.
 - ENH: stop() method allows early termination of Stan sampling
 - ENH: Setting 'verbose' allows for dynamic control of output
 - Remove 'seed' (see RNG note above)
 - Method for checking sample sizes updated to account for the possibility
   that user terminates sampling early. Each chain and each parameter can
   have different lengths
 - permute_index() and extract() updated to account for potentially
   different chain lengths
 - ENH: block() method that blocks Matlab until Stan is finished and data
   is loaded into workspace. This is primarily useful for scripts, where
   further Matlab processing is contingent on the model finishing.

stan
 - Pass through user-defined inits to StanModel