FIX: Minor fixes to text and better warnings for gloo

Ready for review/merge.
This makes it so that we get warnings like:
```
WARNING: Copying discontiguous data for struct dtype:
  File "/Users/larsoner/custombuilds/euroscipy2014_talk/demovisuals.py", line 333, in iteration:
    self.vbo_position.set_data(self._particles['position'])
```
This makes it *much* easier to get rid of these warnings in code.