Minor changes

Consistency rocks!
Update README.md

Added a contributing section, and posted a link to the road map
New Destructor mixin

Fixes #99, Closes #92, and resolves #63
Better Destructor mixin

This mixin is better since it is simpler and everything happens at
compile time. I made a mistake last time which caused me to not do it
this way in the first place.
Imports on color.d

Use of min, max, and isNumeric were undefined, so I imported them.
Merge pull request #101 from pataroose/master

Imports on color.d
Fix Sprite's getGlobalBounds

Fixes #102
Wrapped Unit tests inside versions

I did this to give me a way of testing specific parts of the library at
a time instead of needing to run through all of them. I also added a
couple of tests in the graphic section.
Merge pull request #1 from Jebbs/master

pull & merge diff
Fix dup()

- all dup() functions have been changed to properties to match std
- added functioning dup() to sprite.d
Merge pull request #104 from pataroose/master

some changes to dup()
DDoc audio module first pass
DDoc audio module second pass

Entire property blocks are documented instead of each individual
property function.
DDoc audio module third pass

Fixed some paragraphs. We're paying the price of some files being very
wide (due to some long documentation sentences) for the benefit of code
suggestions being more readable.
Merge pull request #105 from pataroose/master

Audio module DDoc
Fixed destructor not mixing in for release builds

One day I'll test everything.
Unit tests and small updates

Almost all graphic classes have unit tests now. Also fixed a couple of
things here and there.
Merge pull request #2 from Jebbs/master

Merge Jebbs updates
RenderStates default made a property
Removed const from RenderTarget getDefaultView