Fixed copy-paste typo.
Some gulp changes.

- gulp can take the names of multiple tasks to run. Use that in npm install instead of spawning two gulp processes.
- Made watch faster and more robust.
Rewrote documentation generator to use the TypeScript syntax tree instead of UglifyJS.
Added support for variables to documentation generator.
Moved ASTWalker to typescript.js and added reference to the AST node with the JSDoc comments.
Get baseType from AST walker instead of JSDoc.
Auto-generate @constructor, @extends, @memberOf, @private and @static from TypeScript AST.