Adjusted link flags for Mac OS X

First, glfw3 builds as libglfw3 by default, so we link against that.
Then, we have to link a few frameworks, to get rid of missing symbols.
Merge pull request #41 from lloeki/master

Adjusted link flags for Mac OS X
Update README.md

Related to #42 and #39
Correct spelling of SetCursorPosition doc comment.
Merge pull request #44 from mewpull/master

Correct spelling of SetCursorPosition doc comment.
Better code reuse