Added support for parallel lines in Morris.Grid

[tiraeth]

This pull request solves issue #100.

Features:

• Goals: Values that you want to achieve someday.
• Events: Time entries that indicates some events over time, e.g. deadlines.

Note: Events works only when @options.parseDate is enabled, thus events works only for time-series charts only.

Events and Goals are implemented in Morris.Grid, so Line, Area, and Bar charts are automatically affected by it (of course, regarding the note above, Events won't work in bar charts).

[oesmith]

Looks good to me 👍

A couple of notes:

• Math.min / Math.max will treat a null as a zero, so you need to be careful of passing nulls
• I'm trying to move away from using $.map towards using coffee-script list comprehensions wherever possible (they look tidier to me 😀)

(see 8faced7 for the changes I made when merging)

[tiraeth]

👍

Coffeescript's reduce is also better than for or $.each in some cases. I used it in Morris.Pie 😀

[dgilperez]

👍

Thanks for this !!! I am happy to see this implemented, really useful :)