Remove dependancy upon Prototype.js

[camerons]

The vector code currently depends on prototype.js. (If you remove prototype.js from examples/GML.js then the application breaks).

I think the problem is due to a dependancy in Style on a hashtable. There might be more.

OpenLayers has moved to break the dependancy upon Prototype in the core so we should continue this policy.

[camerons]

Problem seems to have been fixed by Pierre/Bertil.

GMLTasmania.html doesn't reference prototype.js anymore.

[tschaub]

There were a number of remaining calls to array.clear() lurking around. Changesets 2069, 2072, and 2073 replace these with OpenLayers.Util.clearArray(array).