fix dead link in development.md

Note: using a relative path should make it still work if *both* `development.md` and `milestones.md` get moved to a `doc` subdirectory again in the future.
Merge pull request #3 from gasche/patch-1

doc: fix dead link in development.md
engine: fixed move/assignment constructors/operators of engine
doc/ideas: added matchmaking idea
doc: added opus-tools dependency for media conversion
So much CAPITALS!!!

But really - pretty much every line needed a new one...
Merge pull request #6 from ollyfg/master

doc: fixed up some more capitals in tasks.md
Updated building.md to contain addition step for building on a vanilla Ubuntu 14.10 box
convert: updated list variable name for sorted body snippets, closes #7
Tweaked for better formatting
Updated as per TheJJ comments
Removed redundant packages as per TheJJs comment
Merge pull request #8 from jamesmintram/master

doc: updated building.md for Ubuntu users
readme: added missing word in the windows port section
readme: added bountysource image and link
Fix include of OpenGL headers on OS X systems

On OS X systems, the OpenGL headers are located in an "OpenGl" folder
instead of the "GL" folder they're located in in most other systems.