Version 2.0.1

Bugfix in psga() to increase speed and avoid some errors.

Version 2.0.0

Major rewrite of package for v2:

• Renamed many functions (gcrst -> sgc, arrival -> sga, ft -> glel) to reflect literature.
• Stationary gammacount can be directly computed, obsoleting use of integrate(), approximate computation, and approximate computation vignette
• Simplified vignette to reflect better understanding of theory and to cite more references.