Disable OpenCL platform on known-buggy macs
Change API reference links to 6.0
units on getPMEParameters
Make element basically immutable
Merge pull request #402 from rmcgibbo/docs

Change API reference links to 6.0
Merge pull request #403 from rmcgibbo/units

units on getPMEParameters
Merge pull request #401 from rmcgibbo/disable

Disable OpenCL platform on known-buggy macs
Merge pull request #404 from rmcgibbo/imutable-elements

Make element basically immutable
Merge branch 'master' of http://github.com/SimTk/openmm