[CM] Grace build error on Ubuntu 64bit

[Joel Matthys]

I encountered some build errors in the latest svn of Grace.

CmSupport.cpp, lines 75 & 82:
	error: cast from ‘void*’ to ‘juce::uint32’ loses precision

Replacing uint32 with long allowed the build to continue, and Grace
seems to work OK now. Will it still behave as it should?

I'm thrilled about the new metro features. Grace + live coding should be
a great combo!

Joel