Trick Simulation Environment 15.1.0

This release contains bug fixes and several back ports from main development trunk.

Adds Event File Descriptors and Futexes as choices for thread synchronization
Adds support for Mac OSX 10.11 (El Capitan)
Adds optional var=value support for CP
Fixes GUI crashes during restart
Fixes variable server crashes during restart
Fixes handling of non-ASCII quotation characters in header files