Fix variable name for xf86vmode lib

CMake bug 0006976 has been fixed. However, the variable name is
different than expected.
Merge pull request #48 from Nibe/xf86vmode-fix

Fix variable name for xf86vmode library.
Updated credits and changelog.
Added option for disabling install.
Fixed duplicate events being reported.
Fixed glfwGetFramebufferSize on OS X.
Restored support for Mac OS X 10.6.

Modified during merge.
Added release description.
Fixed process transform when no menu bar.
Cleanup.
Added missing headers to library target.
Started 3.0.2.
Cleanup.
Documentation work.
Added missing file to .gitignore.
Fixed incorrect hint default.

The default for the GLFW_ALPHA_BITS hint was zero instead of 8.
Typecast EGL types to get rid of compile warnings
Merge pull request #60 from Cloudef/EGL

Explicitly cast default EGL display.
Fixed resizing for full screen override redirect.
Cleanup.