[chuck-users] standard library documentation updated

Greetings, We have updated the online documentation for the standard libraries, finally adding descriptions to many functions: http://chuck.cs.princeton.edu/doc/program/stdlib.html The changes will also be reflected in the next version of the ChucK manual (pdf). All items on this guide should be present, with the exception of math.pi, math.twopi, and math.e. Please let us know if you find any problems. Best, Ge!