Graphing and sparklines in lcm-spy

This pull request adds the following features to lcm-spy:

Features:

- Sparklines on all numerical data
- Sparklines are clickable to open a full graph of the data
  - Graph is interactive, supporting pan/zooming like google maps
  - Supports plotting additional lines on the same graph with or without the same axis, or in another graph
- Improves support for large messages by only drawing text (and sparklines) for messages close to the user's view

Bugfixes / improvements:

- Removes annoying blue background / desktop (#1 gripe in our group) while maintaining backwards compatibility with plugins
- Fixes an issue where collapsing a section would not redraw the window
- Fixes scroll wheel very slow in the inspector window
- Enables anti-aliasing in the type inspector
- Allows the user's window manager to place new windows (including the initial lcm-spy window), creating a more consistent experience

New dependancies:

- Adds [jchart2d](http://jchart2d.sourceforge.net/) for graphing
  - Includes jchart2d as a git subtree, pointing at their latest release
  - Automatically builds jchart2d from source and installs via existing autotools scripts
- Adds `ant` as a dependancy for building jchart2d
  - Configure checks for `ant` and throws a warning + disables java if not found

A screenshot:

![chartscreenshot](https://cloud.githubusercontent.com/assets/1299882/4708115/48f8951a-5894-11e4-91ab-0e12df502323.png)